Your search found 4 records
1 Bastiaanssen, Wim G. M.; Karimi, Poolad; Rebelo, Lisa-Maria; Duan, Z.; Senay, G.; Muthuwatta, Lal; Smakhtin, Vladimir. 2014. Earth observation based assessment of the water production and water consumption of Nile Basin agro-ecosystems. Remote Sensing, 6(11):10306-10334. [doi: https://doi.org/10.3390/rs61110306]
Water requirements ; Water use ; Water accounting ; Water balance ; Groundwater ; Earth observation satellites ; Assessment ; Agroecosystems ; River basins ; Evapotranspiration ; Remote sensing ; Models ; Rain / Africa / Nile Basin
(Location: IWMI HQ Call no: e-copy only Record No: H046822)
(2.06 MB) (2.06 MB)
The increasing competition for water resources requires a better understanding of flows, fluxes, stocks, and the services and benefits related to water consumption. This paper explains how public domain Earth Observation data based on Moderate Resolution Imaging Spectroradiometer (MODIS), Second Generation Meteosat (MSG), Tropical Rainfall Measurement Mission (TRMM) and various altimeter measurements can be used to estimate net water production (rainfall (P) > evapotranspiration (ET)) and net water consumption (ET > P) of Nile Basin agro-ecosystems. Rainfall data from TRMM and the Famine Early Warning System Network (FEWS-NET) RainFall Estimates (RFE) products were used in conjunction with actual evapotranspiration from the Operational Simplified Surface Energy Balance (SSEBop) and ETLook models. Water flows laterally between net water production and net water consumption areas as a result of runoff and withdrawals. This lateral flow between the 15 sub-basins of the Nile was estimated, and partitioned into stream flow and non-stream flow using the discharge data. A series of essential water metrics necessary for successful integrated water management are explained and computed. Net water withdrawal estimates (natural and humanly instigated) were assumed to be the difference between net rainfall (Pnet) and actual evapotranspiration (ET) and some first estimates of withdrawals—without flow meters—are provided. Groundwater-dependent ecosystems withdraw large volumes of groundwater, which exceed water withdrawals for the irrigation sector. There is a strong need for the development of more open-access Earth Observation databases, especially for information related to actual ET. The fluxes, flows and storage changes presented form the basis for a global framework to describe monthly and annual water accounts in ungauged river basins.
2 Karimi, P.; Bastiaanssen, Wim G. M.; Sood, Aditya; Hoogeveen, J.; Peiser, L.; Bastidas-Obando, E.; Dost, R. J. 2015. Spatial evapotranspiration, rainfall and land use data in water accounting - Part 2: reliability of water acounting results for policy decisions in the Awash Basin. Hydrology and Earth System Sciences, 19:533-550. [doi: https://doi.org/10.5194/hess-19-533-2015]
Water accounting ; Land use ; Rain ; Evapotranspiration ; Policy making ; Decision making ; River basins ; Remote sensing ; Satellite surveys ; Indicators ; Hydrology ; Case studies / Ethiopia / Awash Basin
(Location: IWMI HQ Call no: e-copy only Record No: H046821)
http://www.hydrol-earth-syst-sci.net/19/533/2015/hess-19-533-2015.pdf
https://vlibrary.iwmi.org/pdf/H046821.pdf
https://vlibrary.iwmi.org/pdf/H046821.pdf
(6.95 MB) (6.95 MB)
Water Accounting Plus (WA+) is a framework that summarizes complex hydrological processes and water management issues in river basins. The framework is designed to use satellite-based measurements of land and water variables and processes as input data. A general concern associated with the use of satellite measurements is their accuracy. This study focuses on the impact of the error in remote sensing measurements on water accounting and information provided to policy makers. The Awash Basin in the central Rift Valley in Ethiopia is used as a case study to explore the reliability of WA+ outputs, in the light of input data errors. The Monte Carlo technique was used for stochastic simulation of WA+ outputs over a period of 3 yr. The results show that the stochastic mean of the majority of WA+ parameters and performance indicators are within 5 % deviation from the original WA+ values based on one single calculation. Stochastic computation is proposed as a standard procedure for WA+ water accounting because it provides the uncertainty bandwidth for every WA+ output, which is essential information for sound decision-making processes. The majority of WA+ parameters and performance indicators have a coefficient of variation (CV) of less than 20 %, which implies that they are reliable and provide consistent information on the functioning of the basin. The results of the Awash Basin also indicate that the utilized flow and basin closure fraction (the degree to which available water in a basin is utilized) have a high margin of error and thus a low reliability. As such, the usefulness of them in formulating important policy decisions for the Awash Basin is limited. Other river basins will usually have a more accurate assessment of the discharge in the river mouth.
3 Karimi, P.; Bastiaanssen, Wim G. M.. 2015. Spatial evapotranspiration, rainfall and land use data in water accounting - Part 1: review of the accuracy of the remote sensing data. Hydrology and Earth System Sciences, 19:507-532. [doi: https://doi.org/10.5194/hess-19-507-2015]
Water accounting ; Water balance ; Land use ; Rain ; Evapotranspiration ; Remote sensing ; Satellite surveys ; River basins ; Hydrology ; Models
(Location: IWMI HQ Call no: e-copy only Record No: H046824)
http://www.hydrol-earth-syst-sci.net/19/507/2015/hess-19-507-2015.pdf
https://vlibrary.iwmi.org/pdf/H046824.pdf
https://vlibrary.iwmi.org/pdf/H046824.pdf
(0.50 MB) (515 KB)
The scarcity of water encourages scientists to develop new analytical tools to enhance water resource management. Water accounting and distributed hydrological models are examples of such tools. Water accounting needs accurate input data for adequate descriptions of water distribution and water depletion in river basins. Ground-based observatories are decreasing, and not generally accessible. Remote sensing data is a suitable alternative to measure the required input variables. This paper reviews the reliability of remote sensing algorithms to accurately determine the spatial distribution of actual evapotranspiration, rainfall and land use. For our validation we used only those papers that covered study periods of seasonal to annual cycles because the accumulated water balance is the primary concern. Review papers covering shorter periods only (days, weeks) were not included in our review. Our review shows that by using remote sensing, the absolute values of evapotranspiration can be estimated with an overall accuracy of 95 % (SD 5 %) and rainfall with an overall absolute accuracy of 82 % (SD 15 %). Land use can be identified with an overall accuracy of 85 % (SD 7 %). Hence, more scientific work is needed to improve the spatial mapping of rainfall and land use using multiple space-borne sensors. While not always perfect at all spatial and temporal scales, seasonally accumulated actual evapotranspiration maps can be used with confidence in water accounting and hydrological modeling.
4 van Eekelen, M. W.; Bastiaanssen, Wim G. M.; Jarmain, C.; Jackson, B.; Ferreira, F.; van der Zaag, P.; Okello, A. S.; Bosch, J.; Dye, P.; Bastidas-Obando, E.; Dost, R. J. J.; Luxemburg, W. M. J. 2015. A novel approach to estimate direct and indirect water withdrawals from satellite measurements: a case study from the Incomati basin. Agriculture, Ecosystems and Environment, 200:126-142. [doi: https://doi.org/10.1016/j.agee.2014.10.023]
Water resources ; Water use ; Satellite observation ; Measurement ; Mapping ; Estimation ; Stream flow ; Land use ; Wetlands ; Afforestation ; Rain ; Evaporation ; Irrigation water ; Irrigated farming ; Water allocation ; River basins ; Case studies / South Africa / Swaziland / Mozambique / Incomati River Basin
(Location: IWMI HQ Call no: e-copy only Record No: H046891)
http://www.sciencedirect.com/science/article/pii/S0167880914004861/pdfft?md5=c6908de8be95291b7331c9ff266b5eb2&pid=1-s2.0-S0167880914004861-main.pdf
https://vlibrary.iwmi.org/pdf/H046891.pdf
https://vlibrary.iwmi.org/pdf/H046891.pdf
(5.63 MB) (5.63 MB)
The Incomati basin encompasses parts of South Africa, Swaziland and Mozambique, and is a water stressed basin. Equitable allocation of water is crucial to sustain livelihoods and agro-ecosystems, and to sustain international agreements. As compliance monitoring of water distribution by flow meters is laborious, expensive and only partially feasible, a novel approach has been developed to estimate water withdrawals using satellite measurements. Direct withdrawals include pumping from rivers, impoundments and groundwater, for irrigation and other human uses. Indirect withdrawals include evaporation processes from groundwater storage, unconfined shallow aquifers, seepage zones, lakes and reservoirs, and inundations, in addition to evaporation from pristine land surface conditions. Indirect withdrawals intercept lateral flow of water and reduce downstream flow. An innovative approach has been developed that employs three main spatial data layers inferred from satellite measurements: land use, rainfall, and evaporation. The evaporation/rainfall ratio was computed for all natural land use classes and used to distinguish between evaporation from rainfall and incremental evaporation caused by water withdrawals. The remote sensing measurements were validated against measured evaporative flux, stream flow pumping volume, and stream flow reductions. Afforested areas in the whole basin was responsible for an indirect withdrawal of 1241 Mm3/yr during an average rainfall year while the tripartite agreement among the riparian countries specifies a permitted total withdrawal of 546 Mm3/yr. However, the irrigation sector is responsible for direct withdrawals of 555 Mm3/yr only while their allocated share is 1327 Mm3/yr – the long term total withdrawals are thus in line with the tripartite agreement. South Africa withdraws 1504 Mm3/yr while their share is 1261 Mm3/yr. The unmetered stream flow reduction from the afforested areas in South Africa represents the big uncertainty factor. The methodology described using remotely sensed measurements to estimate direct and indirect withdrawals has the potential to be applied more widely to water stressed basins having limited availability of field data.
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