Your search found 6 records
1 Durand, M.; Chen, C.; Frasson, R. P. D. M.; Pavelsky, T. M.; Williams, B.; Yang, X.; Fore, A. 2020. How will radar layover impact SWOT [Surface Water and Ocean Topography] measurements of water surface elevation and slope, and estimates of river discharge? Remote Sensing of Environment, 247:111883. (Online first) [doi: https://doi.org/10.1016/j.rse.2020.111883]
Surface water ; Rivers ; Discharges ; Estimation ; Slope ; Digital elevation models ; Uncertainty ; Topography ; Hydrology ; Interferometry ; Radar imagery
(Location: IWMI HQ Call no: e-copy only Record No: H049831)
(6.71 MB)
Water surface elevation (WSE), slope and width measurements from the forthcoming Surface Water and Ocean Topography (SWOT) mission will enable spaceborne estimates of global river discharge. WSE will be measured by interferometric synthetic aperture radar (InSAR). InSAR measurements are vulnerable to contamination from layover, a phenomenon wherein radar returns from multiple locations arrive at the sensor simultaneously, rendering them indistinguishable. This study assesses whether layover will significantly impact the precision of SWOT estimates of global river discharge. We present a theoretical river layover uncertainty model at the scale of nodes and reaches, which constitute nominal 200 m and 10 km averages, respectively, along river centerlines. The model is calibrated using high-resolution simulations of SWOT radar interaction with topography covering a total of 41,233 node observations, across a wide range of near-river topographic features. We find that height uncertainty increases to a maximum value at relatively low values of topographic standard deviation and varies strongly with position in the swath. When applied at global scale, the calibrated model shows that layover causes expected height uncertainty to increase by only a modest amount (from 9.4 to 10.4 cm at the 68th percentile). The 68th percentile of the slope uncertainty increases more significantly, from 10 to 17 mm/km. Nonetheless, the 68th percentile discharge uncertainty increases only marginally. We find that the impact of layover on SWOT river discharge is expected to be small in most environments.
2 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.
3 Chinnasamy, Pennan; Sood, Aditya. 2020. Estimation of sediment load for Himalayan rivers: case study of Kaligandaki in Nepal. Journal of Earth System Science, 129(1):181. [doi: https://doi.org/10.1007/s12040-020-01437-6]
Sedimentation ; Estimation ; River basins ; Case studies ; Hydropower ; Watershed management ; Soil types ; Water yield ; Sediment yield ; Land use ; Land cover ; Rain ; Hydrology ; Digital elevation models / Nepal / Kaligandaki Basin / Himalayan Rivers
(Location: IWMI HQ Call no: e-copy only Record No: H050007)
(2.42 MB)
Himalayan regions have increasing sediment yield due to undulating topography, slope and improper watershed management. However, due to limited observation data, and site accessibility issues, less studies have quantified sedimentation loads in the Himalayas, especially Nepal. This has hindered the investments on run-of-river hydropower projects as high and unpredicted sedimentation has increased losses in hydropower production. Therefore, there is a need to understand key physical processes driving sedimentation in these regions, with the available data. This study used the Soil and Water Assessment Tool (SWAT) to estimate the sedimentation yields in the Kaligandaki basin of Nepal, which is an important tributary that drains into the Ganges. Multi-source data from field observations, remote sensing platforms, surveys and government records were used to set up and run the SWAT model for the Kaligandaki basin from 2000 to 2009. Results for the 10-year model run indicate that 73% of the total sediment load is estimated to come from the upstream regions (also known as High Himalayan region), while only 27% is contributed from the Middle and High Mountain regions (where land management-based interventions were deemed most feasible for future scenarios). The average sediment concentration was 1986 mg/kg (ppm), with values of 8432 and 12 mg/kg (ppm) for maximum and minimum, respectively. Such high sedimentation rates can impact river ecosystems (due to siltation), ecosystem services and hydropower generation. In addition, model results indicate the need for better high frequency observation data. Results from this study can aid in better watershed management, which is aimed at reducing sedimentation load and protecting Himalayan rivers.
4 Srinet, R.; Nandy, S.; Padalia, H.; Ghosh, Surajit; Watham, T.; Patel, N. R.; Chauhan, P. 2020. Mapping plant functional types in Northwest Himalayan foothills of India using random forest algorithm in Google Earth Engine. International Journal of Remote Sensing, 41(18):7296-7309. [doi: https://doi.org/10.1080/01431161.2020.1766147]
Forests ; Highlands ; Normalized difference vegetation index ; Ecosystems ; Time series analysis ; Moderate resolution imaging spectroradiometer ; Digital elevation models ; Climatic factors ; Mapping / India / Himalayan Foothills
(Location: IWMI HQ Call no: e-copy only Record No: H050791)
(6.51 MB)
Plant functional types (PFTs) have been widely used to represent the vegetation characteristics and their interlinkage with the surrounding environment in various earth system models. The present study aims to generate a PFT map for the Northwest Himalayan (NWH) foothills of India using seasonality parameters, topographic conditions, and climatic information from various satellite data and products using Random Forest (RF) algorithm in Google Earth Engine (GEE) platform. The seasonality information was extracted by carrying out a harmonic analysis of Normalized Difference Vegetation Index (NDVI) time-series (2008 to 2018) from Moderate Resolution Imaging Spectroradiometer (MODIS) Terra surface reflectance 8 day 500 m data (MOD09A1). For topographic information, Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) derived aspect and Multi-Scale Topographic Position Index (MTPI) were used, whereas, for climatic variables, WorldClim V2 Bioclimatic (Bioclim) variables were used. RF, a machine learning classifier, was used to generate a PFT map using these datasets. The overall accuracy of the resulting PFT map was found to be 83.33% with a Kappa coefficient of 0.71. The present study provides an effective approach for PFT classification using different well-established, freely available satellite data and products in the GEE platform. This approach can also be implemented in different ecological settings by using various meaningful variables at varying resolutions.
5 Baghel, S.; Tripathi, M. P.; Khalkho, D.; Al-Ansari, N.; Kumar, A.; Elbeltagi, A. 2023. Delineation of suitable sites for groundwater recharge based on groundwater potential with RS, GIS, and AHP approach for Mand catchment of Mahanadi Basin. Scientific Reports, 13:9860. [doi: https://doi.org/10.1038/s41598-023-36897-5]
Groundwater potential ; Groundwater recharge ; Remote sensing ; Geographical information systems ; Groundwater table ; Drainage ; Land use ; Land cover ; Digital elevation models ; Infiltration ; Soil texture ; Rainfall ; Farmland ; Curvature / India / Chhattisgarh / Mahanadi Basin
(Location: IWMI HQ Call no: e-copy only Record No: H052140)
(3.87 MB) (3.87 MB)
Groundwater management requires a systematic approach since it is crucial to the long-term viability of livelihoods and regional economies all over the world. There is insufficient groundwater management and difficulties in storage plans as a result of increased population, fast urbanisation, and climate change, as well as unpredictability in rainfall frequency and intensity. Groundwater exploration using remote sensing (RS) data and geographic information system (GIS) has become a breakthrough in groundwater research, assisting in the assessment, monitoring, and conservation of groundwater resources. The study region is the Mand catchment of the Mahanadi basin, covering 5332.07 km2 and is located between 21°42'15.525"N and 23°4'19.746"N latitude and 82°50'54.503"E and 83°36'1.295"E longitude in Chhattisgarh, India. The research comprises the generation of thematic maps, delineation of groundwater potential zones and the recommendation of structures for efficiently and successfully recharging groundwater utilising RS and GIS. Groundwater Potential Zones (GPZs) were identified with nine thematic layers using RS, GIS, and the Multi-Criteria Decision Analysis (MCDA) method. Satty's Analytic Hierarchy Process (AHP) was used to rank the nine parameters that were chosen. The generated GPZs map indicated regions with very low, low to medium, medium to high, and very high groundwater potential encompassing 962.44 km2, 2019.92 km2, 969.19 km2, and 1380.42 km2 of the study region, respectively. The GPZs map was found to be very accurate when compared with the groundwater fluctuation map, and it is used to manage groundwater resources in the Mand catchment. The runoff of the study area can be accommodated by the computing subsurface storage capacity, which will raise groundwater levels in the low and low to medium GPZs. According to the study results, various groundwater recharge structures such as farm ponds, check dams and percolation tanks were suggested in appropriate locations of the Mand catchment to boost groundwater conditions and meet the shortage of water resources in agriculture and domestic use. This study demonstrates that the integration of GIS can provide an efficient and effective platform for convergent analysis of various data sets for groundwater management and planning.
6 Tumsa, B. C.; Feyessa, F. F.; Tulluc, K. T.; Guder, A. C. 2023. Spatiotemporal changes of land use in response to runoff and sediment yield for environmental sustainability in the Upper Blue Nile Basin, Oromiyaa, Ethiopia. H2Open Journal, h2oj2023072. [doi: https://doi.org/10.2166/h2oj.2023.072]
Environmental sustainability ; Runoff ; Land use change ; Land cover changes ; Sediment yield ; Satellite imagery ; Soil erosion ; Deforestation ; Rainfall ; Precipitation ; Weather data ; Digital elevation models ; Watersheds / Ethiopia / Oromiyaa / Upper Blue Nile Basin
(Location: IWMI HQ Call no: e-copy only Record No: H052361)
https://iwaponline.com/h2open/article-pdf/doi/10.2166/h2oj.2023.072/1321010/h2oj2023072.pdf
https://vlibrary.iwmi.org/pdf/H052361.pdf
https://vlibrary.iwmi.org/pdf/H052361.pdf
(1.53 MB) (1.53 MB)
Modeling and mapping hydrological responses of runoff and sediment yield to spatiotemporal land use changes are crucial concerning environmental sustainability. The research was aimed at quantifying the spatiotemporal effects of land use on runoff and sediment yields using three land use satellite images and the SWAT+ model. The increase in agriculture, settlement, and decreasing forest goes to the possibility of increasing sediment yield and runoff by 53.2 and 56.5%, respectively, affecting ecosystems. The areas vulnerable to high runoff were found at the lower and middle reaches with the annual average runoff of 10,825.1, 11,972.9, and 13,452 mm for each respective scenario. On the other hand, most of the soil erosion-prone areas designated as severe in the second and third scenarios were covered by agriculture and shrubland, with annual sediment yields of 301.5 and 267.5 tons, respectively. Deforestation for agriculture expansion has a significant role in environmental degradation, as forests play an irreplaceable role in ecological resilience. Generally, the dominant land uses that instigate soil erosion, runoff, and sediment yield are agriculture, shrubland, and deforestation. The simulation of runoff and sediment yield in response to land use change using the SWAT+ model is more scientifically reliable and acceptable.
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