Spatial evapotranspiration, rainfall and land use data in water accounting – Part 2: Reliability of water accounting results for policy decisions in the Awash basin

Abstract

Abstract. 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 as input data. A 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 three years. The results show that the stochastic mean of the majority of WA+ parameters and performance indicators are within 5% deviation from the original values. Stochastic simulation can be used as part of a standard procedure for WA+ water accounting because it provides the error bandwidth for every WA+ output, which is essential information for sound decision making. The majority of WA+ parameters and performance indicators have a Coefficient of Variation (CV) of less than 20% which implies that they are reliable. The results 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 it is recommended that they are not used to formulate important policy decisions.

Geospatial Techniques for Improved Water Management in Jordan

“…At the water basin level, the major components of these systems are the resource base, which represents water supply, crop evapotranspiration and water withdrawal, which represent water depletion, and the biomass production, which represents water productivity [16][17][18]. The most important inputs provided by remote sensing to the abovementioned components are the crop evapotranspiration and the land use maps [19]. The contribution of remote sensing and geospatial techniques will become more important in ungauged and poorly gauged basins as inputs will be provided with low cost and at reasonable accuracy [19].…”

“…The most important inputs provided by remote sensing to the abovementioned components are the crop evapotranspiration and the land use maps [19]. The contribution of remote sensing and geospatial techniques will become more important in ungauged and poorly gauged basins as inputs will be provided with low cost and at reasonable accuracy [19]. Whether water accounting systems are implemented or not, remote sensing and geospatial techniques will continue to support water managers and decision makers with information needed for improved water management.…”

Spatial evapotranspiration, rainfall and land use data in water accounting – Part 1: Review of the accuracy of the remote sensing data

“…Our aim is to understand the accuracy of seasonal and annual total values of ET and rainfall because they are of more practical value in water resource management and the errors at this time scale are different from daily and weekly time scales. The companion paper (Karimi et al, 2014) investigates impacts of the errors associated with the satellite measurement for ET, rainfall and land use on the accuracy of WA+ outputs, using a case study from the Awash basin in Ethiopia.…”

Modeling for Inter-Basin Groundwater Transfer Identification: The Case of Upper Rift Valley Lakes and Awash River Basins of Ethiopia

“…Groundwater occurs in a very wide spectrum of geological settings. According to Karimi et al, [11] and Ayenew [12], water in the study area is supplied as a result of jointing and fracturing especially in the deeper aquifer region. The yield of water from fractured rock is dependent upon the frequency and interconnectedness of flow pathways.…”