Your search found 84 records
1 Mai, V. T.; Van Keulen, H.; Hoanh, Chu Thai; Hessel, R. 2008. Spatial simulation of nitrogen leaching from intensive agriculture in northern Vietnam. In Proceedings of International Symposium on GeoInformatics for Spatial-Infrastructure Development in Earth and Allied Sciences (GIS-IDEAS), Hanoi, Vietnam, 4-6 December 2008. Wageningen, Netherlands: Wageningen UR Publication. pp.383-388.
Simulation models ; Calibration ; Nitrogen fertilizers ; Leaching ; Irrigated farming ; Groundwater ; Percolation ; Intensive farming ; Spatial distribution ; Vegetables ; Cabbages / Vietnam / Tam Duong District
(Location: IWMI HQ Call no: e-copy only Record No: H041856)
http://wgrass.media.osaka-cu.ac.jp/gisideas08/viewpaper.php?id=288
https://vlibrary.iwmi.org/pdf/H041856.pdf
https://vlibrary.iwmi.org/pdf/H041856.pdf
(0.21 MB)
2 Steenhuis, T. S.; Easton, Z. M.; Awulachew, Seleshi Bekele; Ahmed, A. A.; Bashar, K. E.; Adgo, E.; Selassie, Y. G.; Tilahun, S. A. 2012. The Nile Basin sediment loss and degradation, with emphasis on the Blue Nile. In Awulachew, Seleshi Bekele; Smakhtin, Vladimir; Molden, David; Peden D. (Eds.). The Nile River Basin: water, agriculture, governance and livelihoods. Abingdon, UK: Routledge - Earthscan. pp.112-132.
River basins ; Sedimentation ; Sediment pollution ; Runoff ; Highlands ; Gully erosion ; Simulation models ; Reservoirs ; Watersheds ; Assessment ; Water balance ; Spatial distribution / Africa / Nile River Basin / Blue Nile River Basin
(Location: IWMI HQ Call no: IWMI Record No: H045314)
(1.40MB)
3 Lagudu, Surinaidu; Rao, V. V. S. G.; Prasad, P. R.; Sarma, V. S. 2013. Use of geophysical and hydrochemical tools to investigate seawater intrusion in coastal alluvial aquifer, Andhra Pradesh, India. In Wetzelhuetter, C. (Ed.). Groundwater in the coastal zones of Asia-Pacific. Dordrecht, Netherlands: Springer. pp.49-65. (Coastal Research Library Volume 7)
Hydrogeology ; Salt water intrusion ; Coastal area ; Aquifers ; Contamination ; Urban wastes ; Deltas ; Canals ; Irrigation water ; Spatial distribution ; Ions ; Surveys / India / Andhra Pradesh / Godavari Delta
(Location: IWMI HQ Call no: 551.457 G570 WET Record No: H046328)
(1.48 MB)
India has a very long coastline and 25 % of the country’s population live in the coastal zone. Urban centers are located along the coast and three out of four metro cities are located on the coast. The high population density along the banks of major rives and coast Increasing population and demand for water putting the coastal aquifers under stress and causing sea water inrush and salinity upcoming in the coastal aquifers. Apart from sea water contamination, urban waste releases and agriculture inputs threatening the coastal groundwater aquifer systems. Generally coastal areas receive more pollutant loads from different sources including geogenic and anthropogenic sources. Central Godavari delta is located adjacent to the Bay of Bengal Coast, Andhra Pradesh, India and is drained by Pikaleru, Kunavaram and Vasalatippa drains. The area is occupied by recent Quaternary alluvium and gone through a series of marine transgression and regression. The entire study area comes under Godavari central canal command area, water is available throughout year except first week of June and last week of April in the canals. Water requirements for irrigation met from surface water in the delta. There is no groundwater pumping for agriculture as wells as for domestic purpose due to brackish nature of the groundwater at shallow depths. The groundwater depths varying from 0.8 to 3.4 m dug wells and in bore wells located near the coast 4.5–13.3 m. The established groundwater flow direction is to be towards Bay of Bengal from Amalapuram. Geophysical and hydrochemical tools were applied to identify the source of the salinity and to assess the saline water intrusion in the Godavari delta. Electrical Resistivity Tomography (ERT) surveys were carried out at several locations in the deltaic region to delineate the aquifer geometry and to identify saline water aquifer zones. The results inferred from ERT indicate 12–15 m thick loamy sands were existed from surface to subsurface and it is followed by 18–25 m thick clay layers. The thickness of clay is being increased toward Sea from inland. The low resistivity values in the delta are attributed to existence of the thick marine clays in the subsurface and relative high resistivities are attributed to existence of fresh water. The resistivity values similar to saline water <0.01 Om is attributed to the mixing of the saline water along surface water drains. In the Ravva Onshore Terminal low resistivity values indicated up coning of brines and mixing of saline water from Pikaleru drain. Groundwater samples were collected and analyzed for major ions (pH, EC, Ca2+, Mg2+, Na+, F-, HCO3 2-, Cl-, SO4 2-, NO3 -). The elevated TDS, Na+ and Cl is due to dilution of clay minerals upstream and in the downstream mixing of sea water along the drains in the pre monsoon. The quality is being increase in the post monsoon season. The molar ratios of Na+2/Cl (>0.86) and SO4 -2/Cl- (<0.05) in the pre monsoon indicated strong influence of sea water and in the post monsoon increased Na+2/Cl- and SO4 -2/Cl- (>0.05) indicated marine palaeo salinity, dilution of marine clays and dissolution of evaporites. The high SO4 -2/Cl in the post monsoon is attributed to dilution groundwater salinity due to rainfall infiltration and irrigation return flows in the delta. The low Na+2/Cl- ratios in upstream of the delta are due to sand exposures and isolated fresh water lances in the perched aquifers.
4 Chandrasiri, J. K. M. D. 2010. Impact of informal land transactions in settlement schemes in Sri Lanka. Colombo, Sri Lanka: Hector Kobbekaduwa Agrarian Research and Training Institute (HARTI). 69p. (HARTI Research Report 132)
Land transfers ; Land management ; Tenure ; Mortgages ; Settlement ; Irrigation schemes ; Farmers ; Spatial distribution ; Socioeconomic environment ; Investment ; Income ; Case studies / Sri Lanka / Parakrama Samudra Scheme / Udawalawa / Mahaweli H System / Kirindi Oya Scheme
(Location: IWMI HQ Call no: 333.33 G744 CHA Record No: H046409)
(0.31 MB)
5 Panda, D. K.; Mishra, Atmaram; Kumar, A.; Mandal, K. G.; Thakur, A. K.; Srivastava, R. C. 2014. Spatiotemporal patterns in the mean and extreme temperature indices of India, 1971–2005. International Journal of Climatology, 34(13):3585-3603. [doi: https://doi.org/10.1002/joc.3931]
(Location: IWMI HQ Call no: e-copy only Record No: H046422)
This study provides the comprehensive analysis of changes in mean and extreme temperature indices of India to assist the climate change mitigation and adaptation strategies and to add information for the global comparisons, using a high-resolution daily gridded temperature data set (1 ×1 ) during 1971–2005. In addition to the indices recommended by the World Meteorological Organization/CLIVAR Expert Team on Climate Change Detection and Indices, few more indices having social and agricultural implication are investigated at the seasonal and annual scales, utilizing widely adopted statistical methodologies in climate research. The results show, in general, a robust signal of warming, broadly consistent with what has been observed and predicted in other parts of the world in the context of global warming. The frequency and intensity of warm extremes, especially representing the daily minimum temperature, have increased with simultaneous decreases in cold extremes in large parts of the country, but the spatial distribution of the trend magnitude reflects the complex natural climatic settings of India and its possible interaction with the anthropogenic forcing. Seasonal analysis reveals a faster warming in day and night temperatures in winter affecting the major wheat crop. In summer, however, both human and ecosystems appear to be more vulnerable to the increasing tendency of the heatwave occurrences, particularly during night-time, since the 1990s. The relationship with the large-scale natural climatic modes indicates that the warming indices tend to increase in the year following the El Ni˜no events as evident from the correlation with the NINO3.4 index, with a relatively higher association in the monsoon season. Moreover, the concurrent correspondence of the summer heatwaves with the north Indian Ocean sea surface temperature suggests a degree of predictability of the heat stress episode.
6 Karimi, Poolad. 2014. Water accounting plus for water resources reporting and river planning. [PhD thesis funded by IWMI through the CGIAR Research Programme on Water Land and Ecosystems] Delft, Netherlands: Delf University of Technology. 158p. [doi: https://doi.org/10.4233/uuid:3e51a4d9-bfd8-49c0-8100-73fb46bdebc2]
Water accounting ; Water resources ; Water use ; River basins ; Evapotranspiration ; Indicators ; Precipitation ; Remote sensing ; Rain ; Spatial distribution ; Data ; Land use ; Land cover ; Biomass ; Groundwater ; Water storage ; Hydrology ; Satellite observation ; Measurement ; Case studies / Pakistan / Ethiopia / Indus Basin / Awash Basin
(Location: IWMI HQ Call no: IWMI Record No: H046456)
http://repository.tudelft.nl/assets/uuid:3e51a4d9-bfd8-49c0-8100-73fb46bdebc2/Poolad_KARIMI_PhD_Thesis.pdf
https://vlibrary.iwmi.org/pdf/H046456.pdf
https://vlibrary.iwmi.org/pdf/H046456.pdf
(11.93 MB) (11.93 MB)
7 Karimi, Poolad. 2014. Water accounting plus for water resources reporting and river planning. [PhD thesis funded by IWMI through the CGIAR Research Programme on Water Land and Ecosystems] Delft, Netherlands: Delf University of Technology. 158p.
Water accounting ; Water resources ; Water use ; River basins ; Evapotranspiration ; Indicators ; Precipitation ; Remote sensing ; Rain ; Spatial distribution ; Data ; Land use ; Land cover ; Biomass ; Groundwater ; Water storage ; Hydrology ; Satellite observation ; Measurement ; Case studies / Pakistan / Ethiopia / Indus Basin / Awash Basin
(Location: IWMI HQ Call no: IWMI c2 Record No: H046457)
(11.93 MB)
8 Petropoulos, G. P. 2014. Remote sensing of energy fluxes and soil moisture content. Boca Raton, FL, USA: CRC Press. 506p.
Remote sensing ; Energy balance ; Soil moisture ; Soil properties ; Hydrology ; Models ; Climate change ; Heat ; Flooding ; Agroecosystems ; Spatial distribution ; Evapotranspiration ; Radar ; Satellite observation ; Environmental factors ; Land use ; Vegetation ; Measurement ; Case studies ; Solar radiation ; Water balance / Brazil
(Location: IWMI HQ Call no: 551.52530287 G000 PET Record No: H046471)
(0.44 MB)
9 Haile, Alemseged Tamiru; Yan, F.; Habib, E. 2015. Accuracy of the CMORPH satellite-rainfall product over Lake Tana Basin in eastern Africa. Atmospheric Research, 163:177-187. [doi: https://doi.org/10.1016/j.atmosres.2014.11.011]
Rain ; Satellites ; River basins ; Lakes ; Remote sensing ; Spatial distribution ; Wet season ; Dry season / Eastern Africa / Lake Tana Basin
(Location: IWMI HQ Call no: e-copy only Record No: H046880)
In this study, we assessed the accuracy of rainfall occurrence, amount and distribution over the Lake Tana basin in Ethiopia, Eastern Africa, as represented in the NOAA satellite-based Climate Prediction Center Morphing technique (CMORPH) rainfall product. This analysis is carried out at high spatial and temporal resolutions (8 × 8 km2 and daily) using observations from rain gauges as a reference for the period covering January 2003 to December 2006. Graphical comparisons and several statistical metrics such as bias, correlation coefficient, and standard deviation of rainfall differences are used to perform the evaluation analysis. Spatial maps of these statistical metrics were developed to assess the spatial dependency in the CMORPH accuracy. The bias is decomposed into different components, hit, missed, and false, in order to gain additional insight into the possible sources of systematic deviations in CMORPH. Overall, CMORPH was able to capture the seasonal and spatial patterns of rainfall over the basin, but with varying degrees of accuracy that depend on topography, latitude and lake-versus-land conditions within the basin. The results show that CMORPH captured rain occurrence relatively well in both wet and dry seasons over the southern part of the basin but it significantly overestimated those over the lake and its southern shore. The bias of CMORPH in the study area is characterized by seasonal and spatial variations (-25 to 30% in wet season and -40 to 60% in dry season). False as well as missed rains contribute significantly to the total rainfall amounts over the basin. Significant levels of the differences are observed at the daily resolution of CMORPH. The relation between CMORPH and gauge rainfall amounts is stronger (correlationmostly N0.4) in thewet season than in the dry (mostly b0.4).
10 Schmitter, Petra; Zwart, S. J.; Danvi, A.; Gbaguidi, F. 2015. Contributions of lateral flow and groundwater to the spatio-temporal variation of irrigated rice yields and water productivity in a West-African inland valley. Agricultural Water Management, 152:286-298. [doi: https://doi.org/10.1016/j.agwat.2015.01.014]
Groundwater ; Water table ; Flow discharge ; Spatial distribution ; Irrigation ; Rice ; Water productivity ; Water resources ; Water management ; Water balance ; Inland waters ; Valleys ; Crop performance ; Fertilizer application ; Soil organic matter / West Africa
(Location: IWMI HQ Call no: e-copy only Record No: H046882)
Water management techniques to elevate rice yields and productive use of water resources in Africa, frequently lack a substantial spatial assessment as they are often based on plot level measurements without taking into account toposequential effects present in the landscape. These effects have been shown to significantly affect spatio-temporal variations in water availability and rice productivity in Asia. Therefore, this study addresses the spatio-temporal variations of the various water components within irrigated toposequences in an African inland valley and assesses its effect on water productivity and respective rice yields for two irrigation practices: (i) continuous flooding (CF), a well-known water management practice in rice cultivation used worldwide and (ii) a reduced irrigation scheme (RI) where irrigation is applied every 5 days resulting in a 1–2 cm water layer after irrigation. The lateral flow observed in the inland valley had a strong two-dimensional character, contributing to water gains between fields, located at the same toposequential level as well as along toposequences. The toposequential effect on sub-surface hydrological processes masked the overall effect of water management treatment on rice production. Additionally, the associated water productivity (WP) was not found to differ significantly between the treatments when standard calculations (i.e. net irrigation and evapotranspiration) were used but a clear toposequential effect was found for the fertilized lower lying fields when the net irrigation was corrected by the lateral flow component. Results of the established mixed regression model indicated that based on the groundwater table, rainfall and standard soil physico-chemical characteristics rice yields can be predicted in these African inland valleys under continuous flooding and reduced irrigation practices. Validation of the established regression function of inland valleys, representing various groundwater tables in the region, could lead to improved regression functions suitable to estimate spatial variation in rice production and water consumption across scales as affected by water management, fertilizer application and groundwater tables.
11 Zhang, Y.; Holzapfel, C.; Yuan, X. 2013. Scale-dependent ecosystem service. In Wratten, S.; Sandhu, H.; Cullen, R.; Costanza, R. (Eds.). Ecosystem services in agricultural and urban landscapes. Chichester, UK: John Wiley. pp.107-121.
Ecosystem services ; Economic value ; Landscape ; Spatial distribution ; Biodiversity ; Urban areas ; Decision making ; Case studies / USA / China / New York / Qinghai-Tibet Plateau
(Location: IWMI HQ Call no: e-copy only Record No: H047092)
(0.08 MB)
The scale-dependent feature of ecosystem services is embodied in the scale dependency of ecosystem provider, ecosystem beneficiary, ecosystem service measurement and ecosystem service management. This study discusses each scale-dependent feature of ecosystem services, and two typical case studies are presented to illustrate the scale dependency of ecosystem service. One case deals with a park in one of the world’s largest and most developed metropolitan area (New York), which represents local and regional ecosystem services of green space in an urbanized area. The other case covers the Tibet plateau, which represents a nature-dominated ecosystem that provides ecosystem services with both regional and global significance. Such hierarchically structured ecosystem services underline the importance of understanding ecosystem service in an integrated and comprehensive perspective.
12 Amarnath, Giriraj; Rajah, Ameer. 2016. An evaluation of flood inundation mapping from MODIS and ALOS satellites for Pakistan. Geomatics, Natural Hazards and Risk, 7(5):1526-1537. [doi: https://doi.org/10.1080/19475705.2015.1084953]
Natural disasters ; Disaster risk management ; Flooding ; Satellite imagery ; Mapping ; Spatial distribution ; Rain ; River basins / Pakistan / Indus River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047188)
http://www.tandfonline.com/doi/pdf/10.1080/19475705.2015.1084953
https://vlibrary.iwmi.org/pdf/H047188.pdf
https://vlibrary.iwmi.org/pdf/H047188.pdf
(1.09 MB)
The paper presents a moderate resolution imaging spectroradiometer (MODIS) time-series imagery-based algorithm for detection and mapping of seasonal and annual changes in flood extent, and tests this using the flooding of the Indus River Basin in 2010 – one of the greatest recent disasters that affected more than 25 million people in Pakistan. The algorithm was applied to produce inundation maps for 10 annual flood seasons over the period from 2000 to 2011. The MODIS flood products were validated in comparison with advanced land observing system (ALOS) sensors, which have both advanced visible and near infrared radiometer and phased array type L-band synthetic images using the flood fraction comparison method. A simple threshold method is created to cluster the data to identify the flood pixels in the imagery. Calculations are then made to estimate a flood area for each resolution. A statistical study is performed to analyze false positive and false negative rates using the ALOS sensors as ‘ground truth’. Comparison of two flood products at a grid size of 10 km resulted in the coefficient of determination range of 0.72–0.97. This research points to a relevant spatial resolution that could be effectively used to obtain accurate mapped products of the extent of the inundated area. The approach can be used to quantify the damage caused by floods.
13 Chandna, P. K.; Nelson, A.; Khan, M. Z. H.; Hossain, M. M.; Rana, M. S.; Mondal, M.; Mohanty, S.; Humphrey, L.; Rashid, F.; Tuong, T. P. 2015. Targeting improved cropping systems in the coastal zone of Bangladesh: a decision tree approach for mapping recommendation domains. In Humphreys, E.; Tuong, T. P.; Buisson, Marie-Charlotte; Pukinskis, I.; Phillips, M. (Eds.). Proceedings of the CPWF, GBDC, WLE Conference on Revitalizing the Ganges Coastal Zone: Turning Science into Policy and Practices, Dhaka, Bangladesh, 21-23 October 2014. Colombo, Sri Lanka: CGIAR Challenge Program on Water and Food (CPWF). pp.522-541.
Cropping systems ; Agricultural development ; Coastal area ; Spatial distribution ; Analysis ; Mapping ; Land use ; High yielding varieties ; Rice ; Seasonal cropping ; Transplanting ; Water management ; Surface water ; Groundwater ; Soil salinity ; Brackish water ; Aquaculture ; Shrimp culture ; Reclaimed land / Bangladesh / Barisal
(Location: IWMI HQ Call no: IWMI Record No: H047211)
https://cgspace.cgiar.org/bitstream/handle/10568/66389/Revitalizing%20the%20Ganges%20Coastal%20Zone%20Book_Low%20Version.pdf?sequence=1
https://vlibrary.iwmi.org/pdf/H047211.pdf
https://vlibrary.iwmi.org/pdf/H047211.pdf
(0.65 MB) (11.9 MB)
14 Knowling, M. J.; Werner, A. D. 2016. Estimability of recharge through groundwater model calibration: insights from a field-scale steady-state example. Journal of Hydrology, 540:973-987. [doi: https://doi.org/10.1016/j.jhydrol.2016.07.003]
Groundwater recharge ; Models ; Calibration ; Estimation ; Hydraulic conductivity ; Aquifers ; Pumping ; Coastal area ; Spatial distribution ; Discharges / South Australia / Uley Basin
(Location: IWMI HQ Call no: e-copy only Record No: H047639)
(2.66 MB)
The ability of groundwater models to inform recharge through calibration is hampered by the correlation between recharge and aquifer parameters such as hydraulic conductivity (K), and the insufficient information content of observation datasets. These factors collectively result in non-uniqueness of parameter estimates. Previous studies that jointly estimate spatially distributed recharge and hydraulic parameters are limited to synthetic test cases and/or do not evaluate the effect of non-uniqueness. The extent to which recharge can be informed by calibration is largely unknown for practical situations, in which complexities such as parameter heterogeneities are inherent. In this study, a systematic investigation of recharge, inferred through model calibration, is undertaken using a series of numerical experiments that include varying degrees of hydraulic parameter information. The analysis involves the use of a synthetic reality, based on a regional-scale, highly parameterised, steady-state groundwater model of Uley South Basin, South Australia. Parameter identifiability is assessed to evaluate the ability of parameters to be estimated uniquely. Results show that a reasonable inference of recharge (average recharge error 100 K values across the 129 km2 study area). The introduction of pumping data into the calibration reduces error in both the average recharge and its spatial variability, whereas submarine groundwater discharge (as a calibration target) reduces average recharge error only. Nonetheless, the estimation of steady-state recharge through inverse modelling may be impractical for real-world settings, limited by the need for unrealistic amounts of hydraulic parameter and groundwater level data. This study provides a useful benchmark for evaluating the extent to which field-scale groundwater models can be used to inform recharge subject to practical data-availability limitations.
15 Ceola, S.; Laio, F.; Montanari, A. 2015. Human-impacted waters: new perspectives from global high-resolution monitoring. Water Resources Research, 51(9):7064-7079. [doi: https://doi.org/10.1002/2015WR017482]
Water resources ; Human behavior ; Geographical distribution ; Spatial distribution ; Monitoring ; Satellite observation ; Remote sensing ; Rivers ; Hydrological data ; Models ; Population density ; Environmental effects
(Location: IWMI HQ Call no: e-copy only Record No: H047641)
(3.53 MB)
The human presence close to streams and rivers is known to have consistently increased worldwide, therefore introducing dramatic anthropogenic and environmental changes. However, a spatiotemporal detailed analysis is missing to date. In this paper, we propose a novel method to quantify the temporal evolution and the spatial distribution of the anthropogenic presence along streams and rivers and in their immediate proximity at the global scale and at a high-spatial resolution (i.e., nearly 1 km at the equator). We use satellite images of nocturnal lights, available as yearly snapshots from 1992 to 2013, and identify five distinct distance classes from the river network position. Our results show a temporal enhancement of human presence across the considered distance classes. In particular, we observed a higher human concentration in the vicinity of the river network, even though the frequency distribution of human beings in space has not significantly changed in the last two decades. Our results prove that fine-scale remotely sensed data, as nightlights, may provide new perspectives in water science, improving our understanding of the human impact on water resources and water-related environments.
16 Voigt, S.; Giulio-Tonolo, F.; Lyons, J.; Kucera, J.; Jones, B.; Schneiderhan, T.; Platzeck, G.; Kaku, K,; Hazarika, M. K.; Czaran, L.; Li, S.; Pedersen, W.; James, G. K.; Proy, C.; Muthike, D. M.; Bequignon, J.; Guha-Sapir, D. 2016. Global trends in satellite-based emergency mapping. Science, 353(6296):247-252. [doi: https://doi.org/10.1126/science.aad8728]
Earth observation satellites ; Satellite imagery ; Natural disasters ; Mapping ; Disaster preparedness ; Spatial distribution ; Population density ; Technological changes ; International cooperation ; Organizations
(Location: IWMI HQ Call no: e-copy only Record No: H047649)
(1.21 MB)
Over the past 15 years, scientists and disaster responders have increasingly used satellite-based Earth observations for global rapid assessment of disaster situations. We review global trends in satellite rapid response and emergency mapping from 2000 to 2014, analyzing more than 1000 incidents in which satellite monitoring was used for assessing major disaster situations. We provide a synthesis of spatial patterns and temporal trends in global satellite emergency mapping efforts and show that satellite-based emergency mapping is most intensively deployed in Asia and Europe and follows well the geographic, physical, and temporal distributions of global natural disasters. We present an outlook on the future use of Earth observation technology for disaster response and mitigation by putting past and current developments into context and perspective.
17 Jayasree, V.; Venkatesh, B. 2015. Analysis of rainfall in assessing the drought in semi-arid region of Karnataka state, India. Water Resources Management, 29(15):5613-5630. [doi: https://doi.org/10.1007/s11269-015-1137-1]
Weather hazards ; Drought ; Precipitation ; Semiarid zones ; Rainfall patterns ; GIS ; Mapping ; Spatial distribution ; Models ; Meteorological stations / India / Karnataka / Deccan Plateau
(Location: IWMI HQ Call no: e-copy only Record No: H047777)
(1.58 MB)
The present study focuses on drought analysis with an aim to understand the drought vulnerability, estimate and map the drought duration and severity in drought prone North Interior Karnataka region, India. A detailed analysis were carried out using rainfall data of more than 178 (with greater than 30 years data) stations to understand the drought characteristics. Rainfall descriptive variability, percentage occurrence of drought incidences and spatial distribution of rainfall were derived. In order to evaluate the drought severity and its extent and to map, method proposed by Ponce et al. (2000) and the Geographic Information System has been used. The method by Ponce et al. (2000) characterize drought based on intensity, duration and recurrence interval using mean annual precipitation of a location. The results obtained for the study area indicate that, the region is mostly semi-arid with drought occur for more than 50 % of the time. The majority of the drought events are of moderate intensity with few extreme intensity events. Further, it is noticed that, in many station, the rainfall show a decreasing trend. Since, rainfall in this region are mostly declining due to climatic change, the area would experience increasing drought severity in the forthcoming years. The outcome of the study would be useful in understanding the drought pattern, severity and extent in the study area which can be used by scientists and water management professionals to plan drought mitigation measures.
18 Moges, M. A.; Schmitter, Petra; Tilahun, S. A.; Langan, Simon; Dagnew, D. C.; Akale, A. T.; Steenhuis, T. S. 2017. Suitability of watershed models to predict distributed hydrologic response in the Awramba Watershed in Lake Tana Basin. Land Degradation and Development, 28(4):1386-1397. [doi: https://doi.org/10.1002/ldr.2608]
Watershed management ; Hydrology ; Catchment areas ; Models ; Land degradation ; River basin management ; Spatial distribution ; Rainfall-runoff relationships ; Infiltration water ; Wet season ; Calibration ; Groundwater ; Water table ; Water levels / Ethiopia / Lake Tana River Basin / Awramba Watershed
(Location: IWMI HQ Call no: e-copy only Record No: H047780)
Planning effective landscape interventions is an important tool to fight against land degradation and requires knowledge on spatial distribution of runoff. The objective of this paper was to test models that predict temporal and spatial distribution of runoff. The selected models were PED-WM, HBV-IHMS and SWAT. We choose 7 km2 Awramba watershed in the Lake Tana basin with detailed hydrological information for testing these models. Discharge at the outlet, rainfall and distributed information on infiltration rates, water table and extent of the saturated area were collected from 2013 to 2015. The maximum saturated area was 6.5% of the watershed. Infiltration rates exceeded rainfall intensities 91% of the time. Hence saturation excess runoff was the main runoff mechanism. Models were calibrated for the rainy seasons 2013, 2014 and validated for 2015. For daily flow validation, the PED-WM model (Nash Sutcliff efficiency, NSE = 0.61) outperformed HBV-IHMS (NSE = 0.51) and SWAT (NSE = 0.48). Performance on monthly time step was similar. Difference in model behavior depended on runoff mechanism. In PED-WM saturation excess is the main direct runoff process and could predict the maximum extent of the saturated area closely at 6.9%. HBV-IHMS model runoff simulation depended on soil moisture status and evapotranspiration, and hence was able to simulate saturation excess flow but not the extent of the saturated area. In SWAT where infiltration excess is the main runoff mechanism could only predict the monthly discharges well. This study shows that prevailing runoff mechanisms and distribution of runoff source areas should be used for proper model selection.
19 Amarnath, Giriraj; Islam, A. K. M. S.; Shrestha, M. S. 2016. Managing variability: floods and droughts. In Bharati, Luna; Sharma, Bharat R.; Smakhtin, Vladimir (Eds.). The Ganges River Basin: status and challenges in water, environment and livelihoods. Oxon, UK: Routledge - Earthscan. pp.71-92. (Earthscan Series on Major River Basins of the World)
Disaster risk management ; Flooding ; Drought ; Climate change ; Monitoring ; Mapping ; Satellite observation ; Remote sensing ; Spatial distribution ; Monsoon climate ; Rain ; Hydrology ; Models ; Early warning systems ; Forecasting ; Precipitation ; Crop yield ; Population / India / Nepal / Bangladesh / Ganges Basin
(Location: IWMI HQ Call no: IWMI Record No: H047812)
20 Liaqat, U. W.; Awan, U. K.; McCabe, M. F.; Choi, M. 2016. A geo-informatics approach for estimating water resources management components and their interrelationships. Agricultural Water Management, 178:89-105. [doi: https://doi.org/10.1016/j.agwat.2016.09.010]
Water resources ; Water management ; GIS ; Remote sensing ; Groundwater extraction ; Groundwater recharge ; Water supply ; Water use ; Water requirements ; Water scarcity ; Crops ; Evapotranspiration ; Irrigation schemes ; Irrigation canals ; Surface water ; Energy balance ; Models ; Weather data ; Satellite surveys ; Spatial distribution / Pakistan / Indus Basin / Hakra Canal
(Location: IWMI HQ Call no: e-copy only Record No: H047849)
(4.67 MB)
A remote sensing based geo-informatics approach was developed to estimate water resources management (WRM) components across a large irrigation scheme in the Indus Basin of Pakistan. The approach provides a generalized framework for estimating a range of key water management variables and provides a management tool for the sustainable operation of similar schemes globally. A focus on the use of satellite data allowed for the quantification of relationships across a range of spatial and temporal scales. Variables including actual and crop evapotranspiration, net and gross irrigation, net and gross groundwater use, groundwater recharge, net groundwater recharge, were estimated and then their interrelationships explored across the Hakra Canal command area. Spatially distributed remotely sensed estimates of actual evapotranspiration (ETa) rates were determined using the Surface Energy Balance System (SEBS) model and evaluated against ground-based evaporation calculated from the advection-aridity method. Analysis of ETa simulations across two cropping season, referred to as Kharif and Rabi, yielded Pearson correlation (R) values of 0.69 and 0.84, Nash-Sutcliffe criterion (NSE) of 0.28 and 0.63, percentage bias of -3.85% and 10.6% and root mean squared error (RMSE) of 10.6 mm and 12.21 mm for each season, respectively. For the period of study between 2008 and 2014, it was estimated that an average of 0.63 mm day-1 water was supplied through canal irrigation against a crop water demand of 3.81 mm day-1. Approximately 1.86 mm day-1 groundwater abstraction was estimated in the region, which contributed to fulfil the gap between crop water demand and canal water supply. Importantly, the combined canal, groundwater and rainfall sources of water only met 70% of the crop water requirements. As such, the difference between recharge and discharge showed that groundwater depletion was around -115 mm year-1 during the six year study period. Analysis indicated that monthly changes in ETa were strongly correlated (R = 0.94) with groundwater abstraction and rainfall, with the strength of this relationship significantly (p < 0.01 and 0.05) impacted by cropping seasons and land use practices. Similarly, the net groundwater recharge showed a good positive correlation (R) of 0.72 with rainfall during Kharif, and a correlation of 0.75 with canal irrigation during Rabi, at a significance level of p < 0.01. Overall, the results provide insight into the interrelationships between key WRM components and the variation of these through time, offering information to improve the management and strategic planning of available water resources in this region.
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