Your search found 19 records
1 Singh, A. 2016. Managing the water resources problems of irrigated agriculture through geospatial techniques: an overview. Agricultural Water Management, 174:2-10. (Special Issue on Sustainable Water resources Management: Theory and Case Studies, Part I Overseen by Dr. Brent Clothier). [doi: https://doi.org/10.1016/j.agwat.2016.04.021]
Irrigated farming ; Water resources ; Water management ; Groundwater ; Waterlogging ; Soil salinization ; Remote sensing ; GIS ; Spatial variation ; Monitoring techniques ; Case studies / India
(Location: IWMI HQ Call no: e-copy only Record No: H047662)
(1.23 MB)
The intensification of irrigated agriculture is a prerequisite for fulfilling the rising food requirements of the burgeoning global population. But the expansion of irrigated agriculture causes the water resources problems in irrigated areas. The twin menace, i.e., waterlogging and soil salinization of irrigated agriculture can be managed by either adopting preventive measures which decrease the inflow or by employing remedial measures which increase the outflow of water and salt. Remote sensing and geographic information systems (GIS) are very useful tool and offer a good option to traditional techniques in monitoring and evaluation of waterlogged and saline areas. This paper presents an overview of the applications of remote sensing and GIS techniques for the management of water resources problems of irrigated agriculture. The indication and background of the water resources problems are provided. The integrated use of remote sensing and GIS techniques in the management of water resources problems are also discussed. Finally, the case studies of applications of integrated remote sensing and GIS approach and some conclusions are presented.
2 Bhanja, S. N.; Rodell, M.; Li, B.; Saha, D.; Mukherjee, A. 2017. Spatio-temporal variability of groundwater storage in India. Journal of Hydrology, 544:428-437. [doi: https://doi.org/10.1016/j.jhydrol.2016.11.052]
Groundwater table ; Water storage ; Spatial variation ; River basins ; Hydrogeology ; Models ; Precipitation ; Monsoon climate ; Wells ; Measurement ; Monitoring ; Satellite observation ; Costs / India
(Location: IWMI HQ Call no: e-copy only Record No: H047956)
(4.60 MB)
Groundwater level measurements from 3907 monitoring wells, distributed within 22 major river basins of India, are assessed to characterize their spatial and temporal variability. Groundwater storage (GWS) anomalies (relative to the long-term mean) exhibit strong seasonality, with annual maxima observed during the monsoon season and minima during pre-monsoon season. Spatial variability of GWS anomalies increases with the extent of measurements, following the power law relationship, i.e., log-(spatial variability) is linearly dependent on log-(spatial extent). In addition, the impact of well spacing on spatial variability and the power law relationship is investigated. We found that the mean GWS anomaly sampled at a 0.25 degree grid scale closes to unweighted average over all wells. The absolute error corresponding to each basin grows with increasing scale, i.e., from 0.25 degree to 1 degree. It was observed that small changes in extent could create very large changes in spatial variability at large grid scales. Spatial variability of GWS anomaly has been found to vary with climatic conditions. To our knowledge, this is the first study of the effects of well spacing on groundwater spatial variability. The results may be useful for interpreting large scale groundwater variations from unevenly spaced or sparse groundwater well observations or for siting and prioritizing wells in a network for groundwater management. The output of this study could be used to maintain a cost effective groundwater monitoring network in the study region and the approach can also be used in other parts of the globe.
3 Munyati, C. 2015. A spatial analysis of eutrophication in dam reservoir water on the Molopo River at Mafikeng, South Africa. Sustainability of Water Quality and Ecology, 6:31-39. [doi: https://doi.org/10.1016/j.swaqe.2015.01.005]
Water pollution ; Eutrophication ; Dams ; Reservoirs ; Wastewater ; Sewage effluent ; GIS ; Remote sensing ; Satellite imagery ; Spatial variation ; Environmental management ; Plant nutrition ; Rivers / South Africa / Mafikeng / Molopo River / Cooke’s Lake Reservoir / Lotlamoreng Reservoir / Modimola Reservoir / Disaneng Reservoir
(Location: IWMI HQ Call no: e-copy only Record No: H047959)
(1.23 MB)
In water-scarce environments, surface water bodies serve both as water sources and waste disposal channels. The Molopo River that drains through Mafikeng, South Africa, has been dammed for agricultural and municipal water supply, resulting in four reservoirs near Mafikeng. It receives municipal waste water discharges from point pollution source sewage processing plants. In this study the spatial variation in the manifestation of eutrophication in the reservoir water was examined. Surface water samples were collected from the four reservoirs in July (dry season), and analysed for nutrient (NO3 , PO4 3) concentrations. The dry season low river flow period was perceived as the period when the eutrophication problem is more acute. Near infrared (NIR) reflectance from the reservoirs, due to algae and macrophytes like the water lettuce (Pistia stratiotes), was used as manifestation of eutrophication on satellite imagery. The presence of these plant NIR reflectors in the water bodies was assessed using near-concurrent multispectral SPOT 5 images. The image digital number (DN) values were converted to reflectance values. Geostatistical analysis indicated autocorrelation of algal abundance as indicated by the near infrared (NIR, 0.78–0.89 lm) reflectance. Ordinary kriging interpolation indicated change in algal abundance away from the point nutrient sources. Reservoirs with direct effluent point sources had higher nutrient concentrations and NIR reflectance than those without direct point sources. The results indicate the reservoirs to range between eutrophic and hypertrophic, and show the suitability of SPOT 5 imagery for use in the assessment of eutrophication in support of environmental quality assessments for inland water bodies.
4 Gautam, S. K.; Maharana, C.; Sharma, D.; Singh, A. K.; Tripathi, J. K.; Singh, S. K. 2015. Evaluation of groundwater quality in the Chotanagpur plateau region of the Subarnarekha River Basin, Jharkhand State, India. Sustainability of Water Quality and Ecology, 6:57-74. [doi: https://doi.org/10.1016/j.swaqe.2015.06.001]
Groundwater ; Water quality ; Assessment ; Irrigation water ; Drinking water ; Water pollution ; Heavy metals ; Contamination ; Alkaline earth metals ; Sodium ; Magnesium ; Ions ; Salinity ; Chemicophysical properties ; Permeability ; Spatial variation ; Monsoon climate ; Hydrogeology ; Geochemistry ; River basins / India / Jharkhand / Chotanagpur Plateau / Subarnarekha River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047960)
(3.16 MB)
Suitability study of groundwater for domestic and irrigation purposes was carried out in the middle Subarnarekha river basin, Jharkhand. Collected samples were analysed for physicochemical parameters such as conductivity, total dissolved solids (TDS), pH, and heavy metals. After the physicochemical analysis groundwater samples were categorised for simplicity, accordingly, it shows that 52.6% samples fall in Ca-Cl2, 33.3% in Ca-HCO3, 10.5% in Ca-SO4, and 1.7% samples in Mg-HCO3 and rest were Na-Cl type. Interpretation of hydro-geochemical data suggests that leaching of ions followed by weathering and anthropogenic impact (mainly mining and agricultural activities) control the chemistry of groundwater in the study area. The TDS concentration at Govindpur site varies from 2677 mg L1 in the pre-monsoon to 2545 mg L1 in the post-monsoon season that is higher than the BIS (2004-05) maximum permissible limit (2000 mg L1 ). The elevated concentration of NO3 was identified at Govindpur, Hatia Bridge, Kandra, Musabani, Saraikela, Mango and Tatanagar. The higher NO3 concentration was due to the action of leaching and anthropogenic activities. At most of sampling locations, the concentration of Cd, Pb, and Ni were found higher than the prescribed limits defined by BIS and WHO. Groundwater suitability for drinking purpose was also evaluated by the synthetic pollution index (SPI), it suggests that 74%, 95%, and 21% samples fall in seriously polluted category during pre-monsoon, monsoon, and post-monsoon season, respectively. The calculated values of SAR, Na%, RSC, PI, and MH have shown that except at few locations, most of groundwater samples are suitable for irrigation purposes.
5 Ge, Y.; Cai, X.; Zhu, T.; Ringler, C. 2016. Drought frequency change: an assessment in northern India plains. Agricultural Water Management, 176:111-121. [doi: https://doi.org/10.1016/j.agwat.2016.05.015]
Drought ; Frequency ; Climate change ; Assessment ; Precipitation ; Spatial variation ; Models ; Time series analysis ; Crops ; Case studies / Northern India
(Location: IWMI HQ Call no: e-copy only Record No: H047966)
(4.16 MB)
Following the debate on whether drought has become more severe under climate change, this paper assesses drought frequency in northern and eastern India using two datasets of Palmer Drought Severity Index (PDSI) (generated by Dai, 2013 and Sheffield et al., 2012). The univariate return period for three drought characteristics (duration, severity and peak intensity) is examined regarding whether drought has occurred with longer duration, higher severity and/or larger peak intensity. The spatial variation of those changes is analyzed through eight areas in the study region. The temporal and spatial comparisons based on the univariate return period show different change patterns of duration, severity and peak intensity in different areas. Generally, in the areas which plant wheat more than rice (areas 1 and 2), drought has been alleviated in duration and intensity after 1955; while in the areas which plant more rice than wheat (areas 3–8), drought have been aggravated in duration, severity and intensity (except for area 8, a coastal area). This spatial change pattern may imply potential crop pattern change, for example, switching from rice to wheat in areas 3–7. Furthermore, the bivariate return period for pairs of drought characteristics based on the copulas and considering correlation between the drought characteristics is examined to understand how bivariate return periods change over time and space. Finally, it is also found that one data set (Sheffield et al.) results in more severe, longer and more intense drought in most of the areas, especially for the drought events with long-return-periods than the other (Dai).
6 Benin, S. (Ed.) 2016. Agricultural productivity in Africa: trends, patterns, and determinants. Washington, DC, USA: International Food Policy Research Institute (IFPRI). 359p. [doi: https://doi.org/10.2499/9780896298811]
Agricultural production ; Land productivity ; Agricultural development ; Growth rate ; Trends ; Development policies ; Farming systems ; Crop production ; Intensification ; Labour productivity ; Fertilizer application ; Technological changes ; Farmland ; Typology ; Spatial variation ; Development projects ; Performance evaluation ; Sustainability ; Farmers ; Population density ; Market access ; Forests ; Case studies / Africa
(Location: IWMI HQ Call no: 338.16 G100 BEN Record No: H047988)
http://www.ifpri.org/cdmref/p15738coll2/id/130468/filename/130679.pdf
https://vlibrary.iwmi.org/pdf/H047988.pdf
https://vlibrary.iwmi.org/pdf/H047988.pdf
(5.03 MB) (5.03 MB)
7 Serur, A. B.; Sarma, A. K. 2017. Impact of spatial data availability on climate change prediction in the Weyib River Basin in Ethiopia. Water Resources Management, 31(6):1809-1824. [doi: https://doi.org/10.1007/s11269-017-1613-x]
Climate change ; Forecasting ; Spatial variation ; Meteorological stations ; Temperature ; Precipitation ; River basins ; Statistical methods ; Techniques ; Models / Ethiopia / Weyib River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048088)
(3.62 MB)
Impact of spatial data availability on the temperature and precipitation prediction characteristics of Weyib River basin in Ethiopia has been investigated using CMIP5-CanESM2 model for the RCP8.5, RCP4.5 and RCP2.6 scenarios. The objective of the present study is to characterize how future temperatures and precipitation prediction under CMIP5-CanESM2 model output varies against diverse averaged arbitrary spatial weather stations found in the basin. The statistical downscaling model tested and verified using the observed daily data for twelve, six and three averaged arbitrary spatial weather stations as well as for a single weather station was used to predict the future climate scenarios. The results revealed that the mean annual daily maximum and minimum temperature and precipitation for twelve, six and three arbitrary spatial stations have revealed an increasing trend in the upcoming periods until the end of the century. In single station analysis, the trend itself has changed from increasing trend to decreasing trend in case of maximum and minimum temperature. In case of precipitation, no visible trend has been observed in case of single station analysis. Therefore, the variation in amount and distribution of precipitation and temperature among the four averaged spatial stations in the same study area might affect the water resources and agriculture of the basin and also instead of using a single weather station to predict future climate variables for a particular study basin, it is more reliable using averages of numerous spatial weather stations data.
8 Ghosh, S.; Gorain, S.; Mondal, B. 2017. Spatio-temporal variations and links between irrigation and agricultural development in an eastern Indian state. Irrigation and Drainage, 66(5):784-796. [doi: https://doi.org/10.1002/ird.2151]
Agricultural development ; Irrigation management ; Spatial variation ; Water resources ; Groundwater irrigation ; Irrigation canals ; Irrigated land ; Agricultural production ; Growth rate ; Models / India / West Bengal
(Location: IWMI HQ Call no: e-copy only Record No: H048469)
(0.73 MB)
Spatio-temporal variations and links between irrigation and the agricultural sector were delineated in the districts of an eastern Indian state, West Bengal, during 2001–2002 to 2011–2012. Cumulative annual exponential growth rate (CAEGR) was calculated for each of the parameters considered under agriculture and irrigation. The irrigation and agricultural scenario at district level were assessed through different indexes. The growth rate of most of the districts showed a declining trend in 5 out of 11 selected parameters, viz. share of cultivable land to total land, share of net sown area to cultivable land, food grain production, paddy production and cropping intensity. Overall, growth rates were found for the canal- and groundwater irrigated areas, respectively, with an increase of net irrigated area (CAEGR 0.17). Both the agricultural development index (ADI) and the irrigation coverage index (ICI) were found to be high to very high (=60) in four districts, while two districts had very low to low ADI and ICI values (=40) in all the years. The source-wise irrigation utilization indices altogether explained 91% variation in ADI that was predominantly by canal and groundwater irrigation. Some missing links were also observed in some districts where the level of agricultural development did not match the irrigation scenario.
9 Rahman, S.; Sarker, M. R. H.; Mia, M. Y. 2017. Spatial and temporal variation of soil and water salinity in the South-western and South-Central coastal region of Bangladesh. Irrigation and Drainage, 66(5):854-871. [doi: https://doi.org/10.1002/ird.2149]
Soil salinity ; Saline water ; Spatial variation ; Temporal variation ; Rivers ; Water levels ; Surface water ; Groundwater ; Coastal area ; Salt water intrusion ; Agriculture ; Kriging / Bangladesh / Meghna River / Daratona River / Gorai-Madhumati River / Rupsa River / Passur River / Bishkhali River
(Location: IWMI HQ Call no: e-copy only Record No: H048489)
(2.77 MB)
Salinity intrusion is one of the major water-related problems in the coastal region of Bangladesh. The intention of this study was to discuss the spatial distribution of soil and water salinity with their severity levels using geospatial techniques. The spatial analysis shows about 222 300 ha of new land being affected by various degrees of soil salinity during the last four decades. The analysis revealed that the spatial extent of salinity has been following an increasing trend and the movement of soil salinity has moved north from the coast. An increasing trend of salinity concentration in the rivers has already been found in the Lower Meghna River, Alaipur Khal (creek) of Daratona River, Gorai Madhumati, Rupsa Passur River and Bishkhali River in different districts of coastal Bangladesh. The groundwater is contaminated with a high level of salinity, which affects sources of drinking water, agriculture and the irrigation sector. Increased soil and water salinity levels cause an unfavourable environmental and hydrological situation that restricts usual crop production throughout the year. This research will assist decision makers and planners in taking proper initiatives for developing integrated land and water resources management plans for the coastal regions, which have similar environmental settings along the Bay of Bengal.
10 Thomas, J.; Joseph, S.; Thrivikramji, K. P. 2018. Estimation of soil erosion in a rain shadow river basin in the southern Western Ghats, India using RUSLE [Revised Universal Soil Loss Equation] and transport limited sediment delivery function. International Soil and Water Conservation Research, 6(2):111-122. [doi: https://doi.org/10.1016/j.iswcr.2017.12.001]
Erosion ; Estimation ; River basins ; Rainfall-runoff relationships ; Sedimentation ; Models ; Universal soil loss equation ; Land use ; Land cover ; Highlands ; Spatial variation / India / Kerala / Western Ghats / Pambar River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H048778)
https://www.sciencedirect.com/science/article/pii/S2095633917301338/pdfft?md5=e6b98188466fa4cf9da992aa705f38dc&pid=1-s2.0-S2095633917301338-main.pdf
https://vlibrary.iwmi.org/pdf/H048778.pdf
https://vlibrary.iwmi.org/pdf/H048778.pdf
(6.75 MB) (6.75 MB)
Soil erosion and deposition in a tropical mountainous river basin, viz., Pambar River Basin (PRB), in a rain shadow region of the southern Western Ghats (India) were modelled using Revised Universal Soil Loss Equation (RUSLE) and transport limited sediment delivery (TLSD) function in GIS. Mean gross soil erosion in the basin is 11.70 t ha 1 yr 1 , and is comparable with the results of previous soil erosion studies from the region. However, mean net soil erosion from the basin is 2.92 t ha 1 yr 1 only, which is roughly 25% of the gross soil erosion. Although natural vegetation belts show relatively higher gross- and net-soil erosion rates (mainly due to high LS and C factors), their sediment transport efficiency is remarkably less, compared to the land use/ land cover types with anthropogenic signatures (i.e., plantations and croplands). Despite the lesser amount of annual rainfall, the high rates of soil loss from the semi-arid areas of the basin might be the result of the poor protective vegetation cover as well as isolated high intensity rainfall events. The study highlights the significance of climate-specific plans for soil erosion management and conservation of the soil resources of the basins developed in rain shadow regions.
11 Bogale, A.; Aynalem, D.; Adem, A.; Mekuria, Wolde; Tilahun, S. 2020. Spatial and temporal variability of soil loss in gully erosion in Upper Blue Nile Basin, Ethiopia. Applied Water Science, 10(5):106. [doi: https://doi.org/10.1007/s13201-020-01193-4]
Gully erosion ; Soil loss ; Soil conservation ; Water conservation ; Spatial variation ; Groundwater assessment ; Groundwater table ; Stream flow ; Sediment ; Watersheds ; Catchment areas ; Highlands / Ethiopia / Upper Blue Nile Basin / Chentale Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H049937)
https://link.springer.com/content/pdf/10.1007/s13201-020-01193-4.pdf
https://vlibrary.iwmi.org/pdf/H049937.pdf
https://vlibrary.iwmi.org/pdf/H049937.pdf
(1.63 MB) (1.63 MB)
Gully erosion has many negative impacts on both cultivated and grazing lands in Ethiopian highlands. The present study was conducted in Chentale watershed, Ethiopia, to quantify the contribution of gully erosion, and to assess its temporal changes. Within the Chentale watershed, we selected a sub-watershed (104.6 ha) and nested gully catchment, and gauged for stream flow and sediment concentration data in 2015 and 2016. We measured gully dimensions before and after the onset of the rainy season in 2016 to determine soil loss due to gully erosion. The temporal changes of gully expansion were determined by digitizing gully plain area from Google earth images taken in 2005 and 2013. The results support that gullies were expanding at higher rate in recent years. Area covered by gullies in the watershed increased from 1.84 to 3.43 ha between 2005 and 2013, indicating that the proportion of the watershed covered by gullies was nearly doubled in the investigated period. The estimated soil loss from the main watershed and gullies catchment was 6 and 2 t ha-1 year-1 in 2015, and was 7 and 9 t ha-1 year-1 in 2016, respectively. The results support that gullies were the main contributors of soil erosion in the watershed, and that integrated soil and water conservation measures are required to reduce soil erosion.
12 Khan, J. N.; Ali, S. R.; Jillani, A.; Ashraf, I. 2020. Application of RS/GIS in conservation studies for surface and groundwater harvesting in cold arid regions of northwestern Himalayas. Applied Engineering in Agriculture, 36(1):105-114. [doi: https://doi.org/10.13031/aea.13526]
Water harvesting ; Surface water ; Groundwater ; Remote sensing ; Geographical information systems ; Arid zones ; Spatial variation ; Digital elevation models ; Runoff ; Precipitation ; Rain ; Soil texture ; Land use ; Land cover ; Mapping / India / Himalayas / Jammu and Kashmir
(Location: IWMI HQ Call no: e-copy only Record No: H049921)
(1.20 MB)
The availability of erratic rainfall and high evapotranspiration causes temporal and spatial variability of water thereby causing crop yield reduction and crop failure. The potential of water harvesting (WH) both groundwater as well as surface water to mitigate the spatial and temporal variability of precipitation. One technique for water harvesting (WH) is to collect excess runoff water both rain and snowmelt, store it for agricultural purposes during dry spells. The present work accentuated the expediency of remote sensing (RS) and geographic information system (GIS) applications in water harvesting studies. The resultant water harvesting potential map prepared was thus classified into three WH potential zones namely, high, medium and low covering an area of 32.82, 10320.10, and 7596.18 ha (<1%, 57.49%, and 42.32%) respectively. The groundwater map in the area was also classified as high potential areas covering 1421.69 ha (7.92%), medium potential areas covering 8762.69 ha (48.81%), and low potential areas covering 7764.72 ha (43.25%). The integrated remote sensing (RS), Geographical Information System (GIS), Soil and Water Assessment Tool (SWAT), and analytical hierarchy process (AHP) were found to be efficient methods to recover water and to select suitable water and groundwater harvesting sites in order to ensure better water accessibility to the people for domestic, irrigation and other activities in cold arid regions of northwestern Himalayas.
13 Taye, Meron Teferi; Dyer, E.; Charles, K. J.; Hirons, L. C. 2021. Potential predictability of the Ethiopian summer rains: understanding local variations and their implications for water management decisions. Science of the Total Environment, 755(Part 1):142604. [doi: https://doi.org/10.1016/j.scitotenv.2020.142604]
Rain ; Weather forecasting ; Water management ; Decision making ; Oceanic climate ; Temperature ; Climate change ; El Nino-Southern Oscillation ; Precipitation ; Spatial variation ; River basins ; Case studies / Ethiopia / Awash River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H050014)
https://www.sciencedirect.com/science/article/pii/S0048969720361337/pdf?md5=58c744b3a1e31d3bceecd1661ae3f3c3&pid=1-s2.0-S0048969720361337-main.pdf
https://vlibrary.iwmi.org/pdf/H050014.pdf
https://vlibrary.iwmi.org/pdf/H050014.pdf
(4.89 MB) (4.89 MB)
Understanding the influence of large-scale oceanic and atmospheric variability on rainfall over Ethiopia has huge potential to improve seasonal forecasting and inform crucial water management decisions at local levels, where data is available at appropriate scales for decision makers. In this study, drivers of Ethiopia‘s main rainy season, July-September (JAS), are investigated using correlation analysis with sea surface temperature (SST). The analysis showed local spatial variations in the drivers of JAS rainfall. Moreover, the analysis revealed strong correlation between March to May (MAM) SST and JAS rainfall in particular regions. In addition to the influence of SSTs, we highlighted one of the mechanisms explaining the regional pattern of SST influence on Ethiopian rainfall, the East African Low-Level Jet. Moreover, examining the occurrence of large-scale phenomena provided additional information, with very strong ENSO and positive IOD events associated with drier conditions in most part of Ethiopia. A sub-national analysis, focused at a scale relevant for water managers, on the Awash basin, highlighted two distinct climate zones with different relationships to SSTs. June was not included as part of the rainy season as in some areas June is a hot, dry month between rainy seasons and in others it can be used to update sub-seasonal forecasts with lead time of one month for JAS rainfall. This highlights the importance of understanding locally relevant climate systems and ensuing sub-seasonal to seasonal forecasts are done at the appropriate scale for water management in the complex topography and climatology of Ethiopia.
14 Mainali, J.; Chang, H. 2021. Environmental and spatial factors affecting surface water quality in a Himalayan Watershed, Central Nepal. Environmental and Sustainability Indicators, 9:100096. [doi: https://doi.org/10.1016/j.indic.2020.100096]
Surface water ; Water quality ; Environmental factors ; Spatial variation ; Watersheds ; Water pollution ; Land use ; Land cover ; Remote sensing ; Rivers ; Electrical conductivity ; Dissolved oxygen ; Models / Nepal / Himalayan Region / Setikhola Watershed / Pokhara Valley
(Location: IWMI HQ Call no: e-copy only Record No: H050227)
https://www.sciencedirect.com/science/article/pii/S2665972720300805/pdfft?md5=a19c47e58d2541d0695b643a17865928&pid=1-s2.0-S2665972720300805-main.pdf
https://vlibrary.iwmi.org/pdf/H050227.pdf
https://vlibrary.iwmi.org/pdf/H050227.pdf
(2.62 MB) (2.62 MB)
Various spatial interrelationships among sampling stations are not well explored in the spatial modeling of water quality literature. This research explores the relationship between water quality and various social, demographic, and topographic factors in an urbanizing watershed of Nepal with a comparison of different connectivity matrices to conceptualize spatial interrelationships. We collected electrical conductivity and dissolved oxygen data from surface water bodies using a handheld probe and used the data to establish relationships with land use, topography, and population density-based explanatory variables at both watershed and 100-m buffer scales. The linear regression model was compared with different eigenvector-based spatial filtering models. These spatial filtering models were constructed using five different spatial conceptualizations based on different graph types generated from the geographic coordinates of the sampling sites. Population density, elevation, and percentage of sand in the watershed and riparian regions are most important in explaining dissolved oxygen concentration and electric conductivity. A human signature as population density and increased sand and gravel cover can be detected in this watershed impacting water quality. Among different graph types compared, the relative graph type provided the highest model strength signifying a stronger upstream-downstream relationship of dissolved oxygen, while k-nearest graph types with four neighbors provided the strongest model performance, indicating the impact of local factors on electrical conductivity. The relationships between socio-environmental factors and water quality and their spatial interrelationships identified in this work shed light on the source, mobilization, and transport of dissolved oxygen and electrical conductivity and can assist the water quality management endeavor.
15 Alahacoon, Niranga; Edirisinghe, M. 2021. Spatial variability of rainfall trends in Sri Lanka from 1989 to 2019 as an indication of climate change. ISPRS International Journal of Geo-Information, 10(2):84. [doi: https://doi.org/10.3390/ijgi10020084]
Rainfall patterns ; Trends ; Climate change ; Spatial variation ; Weather hazards ; Climatic zones ; Natural disasters ; Precipitation ; Flooding ; Monsoons ; Drought ; Arid zones ; Semiarid zones ; Geographical information systems / Sri Lanka
(Location: IWMI HQ Call no: e-copy only Record No: H050312)
(3.82 MB) (3.82 MB)
Analysis of long-term rainfall trends provides a wealth of information on effective crop planning and water resource management, and a better understanding of climate variability over time. This study reveals the spatial variability of rainfall trends in Sri Lanka from 1989 to 2019 as an indication of climate change. The exclusivity of the study is the use of rainfall data that provide spatial variability instead of the traditional location-based approach. Henceforth, daily rainfall data available at Climate Hazards Group InfraRed Precipitation corrected with stations (CHIRPS) data were used for this study. The geographic information system (GIS) is used to perform spatial data analysis on both vector and raster data. Sen’s slope estimator and the Mann–Kendall (M–K) test are used to investigate the trends in annual and seasonal rainfall throughout all districts and climatic zones of Sri Lanka. The most important thing reflected in this study is that there has been a significant increase in annual rainfall from 1989 to 2019 in all climatic zones (wet, dry, intermediate, and Semi-arid) of Sri Lanka. The maximum increase is recorded in the wet zone and the minimum increase is in the semi-arid zone. There could be an increased risk of floods in the southern and western provinces in the future, whereas areas in the eastern and southeastern districts may face severe droughts during the northeastern monsoon. It is advisable to introduce effective drought and flood management and preparedness measures to reduce the respective hazard risk levels.
16 Adhikari, M. P.; Rawal, N. B.; Adhikari, N. B. 2021. Real-time fine-scale measurement of water quality parameters along the Bagmati River in the Kathmandu Valley. Nature Environment and Pollution Technology, 20(3):1047-1057. [doi: https://doi.org/10.46488/NEPT.2021.v20i03.012]
Water quality ; Chemicophysical properties ; Water pollution ; Rivers ; Observation ; Wastewater ; Spatial variation ; Salinity ; Downstream ; Upstream / Nepal / Kathmandu Valley / Bagmati River / Gokarna / Tilganga / Tinkune / Balkhu
(Location: IWMI HQ Call no: e-copy only Record No: H050657)
(0.99 MB) (0.99 MB)
Real-time fine-scale data was collected along the Bagmati River, in Kathmandu Valley, using mobile and fixed sensor system during the winter season. The water quality parameters; pH, conductivity, total dissolved salt (TDS), salinity, oxygen reduction potential (ORP), dissolved oxygen (DO), and turbidity were measured in the space domain using a fixed sensor and mobile sensor (small rafting boat loaded with sensor) systems. The water quality parameters from the fixed sensor system revealed that the Bagmati River was comparatively less polluted upstream from Gokarna to Tilganga sites and molecular oxygen present in the water was enough to decompose organic pollutants. However, the water quality downstream from Tinkune to Balkhu sites was degraded drastically making it unfit for living organisms. Temporal variation of water quality attributes that human activity significantly enhanced pollutants which severely degraded the water quality in the daytime. The fine-scale space domain heat map data of the mobile sensor system also suggested that the water quality continuously deteriorated from Shankhamul to Sundarighat sites. The ORP value was always negative and decreased with downflow and becomes -263 mV near the Sundarighat Bridge. The mixing of tributaries and increment of solid waste and untreated sewer along the river enhanced pollutants excessively and decreased oxygen level to zero. The results attributed that decomposition of the sewer by microorganism consumed almost all oxygen which produced volatile compounds and generated malodorous odor downstream of Bagmati River.
17 Dembele, Moctar; Vrac, M.; Ceperley, N.; Zwart, Sander J.; Larsen, J.; Dadson, S. J.; Mariethoz, G.; Schaefli, B. 2022. Contrasting changes in hydrological processes of the Volta River Basin under global warming. Hydrology and Earth System Sciences, 26(5):1481-1506. [doi: https://doi.org/10.5194/hess-26-1481-2022]
River basins ; Hydrological cycle ; Global warming ; Hydrological modelling ; Climate change ; Forecasting ; Water availability ; Hydroclimate ; Climatic zones ; Spatial variation ; Datasets / West Africa / Volta River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H051026)
https://hess.copernicus.org/articles/26/1481/2022/hess-26-1481-2022.pdf
https://vlibrary.iwmi.org/pdf/H051026.pdf
https://vlibrary.iwmi.org/pdf/H051026.pdf
(4.33 MB) (4.33 MB)
A comprehensive evaluation of the impacts of climate change on water resources of the West Africa Volta River basin is conducted in this study, as the region is expected to be hardest hit by global warming. A large ensemble of 12 general circulation models (GCMs) from the fifth Coupled Model Intercomparison Project (CMIP5) that are dynamically downscaled by five regional climate models (RCMs) from the Coordinated Regional-climate Downscaling Experiment (CORDEX)-Africa is used. In total, 43 RCM–GCM combinations are considered under three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5). The reliability of each of the climate datasets is first evaluated with satellite and reanalysis reference datasets. Subsequently, the Rank Resampling for Distributions and Dependences (R2D2) multivariate bias correction method is applied to the climate datasets. The bias-corrected climate projections are then used as input to the mesoscale Hydrologic Model (mHM) for hydrological projections over the 21st century (1991–2100).
Results reveal contrasting dynamics in the seasonality of rainfall, depending on the selected greenhouse gas emission scenarios and the future projection periods. Although air temperature and potential evaporation increase under all RCPs, an increase in the magnitude of all hydrological variables (actual evaporation, total runoff, groundwater recharge, soil moisture, and terrestrial water storage) is only projected under RCP8.5. High- and low-flow analysis suggests an increased flood risk under RCP8.5, particularly in the Black Volta, while hydrological droughts would be recurrent under RCP2.6 and RCP4.5, particularly in the White Volta. The evolutions of streamflow indicate a future delay in the date of occurrence of low flows up to 11 d under RCP8.5, while high flows could occur 6 d earlier (RCP2.6) or 5 d later (RCP8.5), as compared to the historical period.
Disparities are observed in the spatial patterns of hydroclimatic variables across climatic zones, with higher warming in the Sahelian zone. Therefore, climate change would have severe implications for future water availability with concerns for rain-fed agriculture, thereby weakening the water– energy–food security nexus and amplifying the vulnerability of the local population. The variability between climate models highlights uncertainties in the projections and indicates a need to better represent complex climate features in regional models. These findings could serve as a guideline for both the scientific community to improve climate change projections and for decision-makers to elaborate adaptation and mitigation strategies to cope with the consequences of climate change and strengthen regional socioeconomic development.
Results reveal contrasting dynamics in the seasonality of rainfall, depending on the selected greenhouse gas emission scenarios and the future projection periods. Although air temperature and potential evaporation increase under all RCPs, an increase in the magnitude of all hydrological variables (actual evaporation, total runoff, groundwater recharge, soil moisture, and terrestrial water storage) is only projected under RCP8.5. High- and low-flow analysis suggests an increased flood risk under RCP8.5, particularly in the Black Volta, while hydrological droughts would be recurrent under RCP2.6 and RCP4.5, particularly in the White Volta. The evolutions of streamflow indicate a future delay in the date of occurrence of low flows up to 11 d under RCP8.5, while high flows could occur 6 d earlier (RCP2.6) or 5 d later (RCP8.5), as compared to the historical period.
Disparities are observed in the spatial patterns of hydroclimatic variables across climatic zones, with higher warming in the Sahelian zone. Therefore, climate change would have severe implications for future water availability with concerns for rain-fed agriculture, thereby weakening the water– energy–food security nexus and amplifying the vulnerability of the local population. The variability between climate models highlights uncertainties in the projections and indicates a need to better represent complex climate features in regional models. These findings could serve as a guideline for both the scientific community to improve climate change projections and for decision-makers to elaborate adaptation and mitigation strategies to cope with the consequences of climate change and strengthen regional socioeconomic development.
18 Maduranga, U. G. D.; Edirisinghe, M.; Alahacoon, Niranga; Ranagalage, M. 2022. Spatiotemporal variability of lightning activity over the railway network in Sri Lanka with special attention to the proposed suburban railway electrification network. Infrastructures, 7(7):92. [doi: https://doi.org/10.3390/infrastructures7070092]
Lightning ; Railways ; Spatial variation ; Transportation ; Safety ; Protection ; Electrification ; Weather hazards ; Vulnerability ; Population density / Sri Lanka
(Location: IWMI HQ Call no: e-copy only Record No: H051311)
https://www.mdpi.com/2412-3811/7/7/92/pdf?version=1657704167
https://vlibrary.iwmi.org/pdf/H051311.pdf
https://vlibrary.iwmi.org/pdf/H051311.pdf
(3.25 MB) (3.25 MB)
This study is oriented towards the investigation of the spatiotemporal variability of the lightning activity over the railway network in Sri Lanka using -lightning data from 1998 to 2014 that were downloaded from the database of Lightning Imaging Sensor (LIS) onboard NASA’s Tropical Rainfall Measuring Mission (TRMM). The study has also been extended to study the lightning activity over the proposed suburban railway electrification network. GIS was used to conduct an annual and seasonal analysis of the railway network, which consists of nine major railway lines, to identify vulnerable stations and segments. The average annual lightning flash density over a 1447 km-long railway network of Sri Lanka varies between 5.08–16.58 flashes/(km2 year). The railway lines run across the western and southern regions of the country have been identified as being in areas with higher lightning activity. In comparison to other railway lines, the Kelani Valley line in the Colombo district and Colombo-Maradana to Polgahawela segment of the Mainline are particularly vulnerable to lightning activity. These areas have also been recognized as regions with higher population density. The proposed 102 km long railway electrification network in Sri Lanka is also within higher population density segments, with higher lightning flash density values between 10.55–16.53 flashes/(km2 ·year). As a result, to improve the operational efficiency of the proposed electrification network, a fully coordinated lightning protection system in accordance with the findings of this study is strongly suggested.
19 Waqas, M. M.; Waseem, M.; Ali, S.; Hopman, J. W.; Awan, Usman Khalid; Shah, S. H. H.; Shah, A. N. 2022. Capturing spatial variability of factors affecting the water allocation plans—a geo-informatics approach for large irrigation schemes. Environmental Science and Pollution Research, 29(54):81418-81429. [doi: https://doi.org/10.1007/s11356-022-20912-9]
Irrigation schemes ; Water allocation ; Plans ; Spatial variation ; Geostatistics ; Geographical information systems ; Remote sensing ; Irrigation water ; Cropping patterns ; Soil texture ; Soil salinity ; Groundwater level ; Water quality ; Irrigation systems ; Canals / Pakistan / Indus Basin Irrigation System / Lower Chenab Canal Irrigation Scheme
(Location: IWMI HQ Call no: e-copy only Record No: H051314)
(1.81 MB)
The livelihoods of poor people living in rural areas of Indus Basin Irrigation System (IBIS) of Pakistan depend largely on irrigated agriculture. Water duties in IBIS are mainly calculated based on crop-specific evapotranspiration. Recent studies show that ignoring the spatial variability of factors affecting the crop water requirements can affect the crop production. The objective of the current study is thus to identify the factors which can affect the water duties in IBIS, map these factors by GIS, and then develop the irrigation response units (IRUs), an area representing the unique combinations of factors affecting the gross irrigation requirements (GIR). The Lower Chenab Canal (LCC) irrigation scheme, the largest irrigation scheme of the IBIS, is selected as a case. Groundwater quality, groundwater levels, soil salinity, soil texture, and crop types are identified as the main factors for IRUs. GIS along with gamma design software GS + was used to delineate the IRUs in the large irrigation scheme. This resulted in a total of 84 IRUs in the large irrigation scheme based on similar biophysical factors. This study provided the empathy of suitable tactics to increase water management and productivity in LCC. It will be conceivable to investigate a whole irrigation canal command in parts (considering the field-level variations) and to give definite tactics for management.
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