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An introduction is presented in which the editor discusses various reports within the issue including the effects of climate change on water availability, freshwater resources and climate change, and water governance.

Abstract: The technical, economic, and ecological aspects of rainwater management are interlinked and spatially bounded. Developing, scaling-out, and targeting rainwater management innovations as adaptive strategies to upgrade rainfed agriculture are therefore preferably best approached through integrated innovations and recommendation domains as a paradigm. At the level of scenario development, the integrated innovations paradigm helps to understand and address integrity between technical, economic, and ecological issues that affect technology adoption, impact, and sustained use. At the level of scaling-out and targeting, recommendation domains provide the spatial dimension that embraces the economic, institutional, biophysical, and agro-ecological conditions in which integrated rainwater management innovations can be accommodated to address heterogeneity. This paper reviews Ethiopia''s experience in rainwater management (adoption, performance, and impact) to get insights about the proposed paradigm and the factors entering the paradigm. The findings suggest that integrated innovations and the conditions of success embraced in a recommendation domain provide the necessary and sufficient conditions for a successful rainwater management intervention at a landscape level. [Copyright &y& Elsevier]

The Mekong River Basin is considered to be the second most species rich river basin in the world. The 795,000km2 catchment encompasses several ecoregions, incorporating biodiverse and productive wetland systems. Eighty percent of the rapidly expanding population of the Lower Mekong Basin (LMB), made up in part by Lao PDR, Thailand, Cambodia and Viet Nam, live in rural areas and are heavily reliant on wetland resources. As the populations of Cambodia and Lao PDR will double in the next 20 years, pressure on natural resources and particularly wetlands can only increase. For development planning, resource and conservation management to incorporate wetland issues, information on the distribution and character of Mekong wetlands is essential. The existing but outdated wetland maps were compiled from secondary land use–land cover data, have limited coverage, poor thematic accuracy and no meta-data. Therefore the Mekong River Commission (MRC) undertook to produce new wetland coverage for the LMB. As resources, funding and regional capacity are limited, it was determined that the method applied should use existing facilities, be easily adaptable, and replicable locally. For the product to be useful it must be accepted by local governments and decision makers. The results must be of acceptable accuracy (>75%) and the methodology should be relatively understandable to non-experts. In the first stage of this exercise, field survey was conducted at five pilot sites covering a range of typical wetland habitats (MRC wetland classification) to supply data for a supervised classification of Landsat ETM images from the existing MRC archive. Images were analysed using ERDAS IMAGINE and applying Maximum Likelihood Classification. Field data were reserved to apply formal accuracy assessment to the final wetland habitat maps, with resulting accuracy ranging from 77 to 94%. The maps produced are now in use at a Provincial and National level in three countries for resource and conservation planning and management applications, including designation of a Ramsar wetland site of international importance. [Copyright &y& Elsevier]

Small-scale farmers face numerous challenges to invest in natural resource management practices. The problems are interlinked, with such perverse economic problems as high transaction costs and risk rooted in the lack of comprehensive institutional and organizational services to farmers for risk reduction and incentive creation. Failure to address such a missing link undermines success in natural resource management. This paper ponders the importance of such a missing link and proposes analytic framework that explicitly integrates the economics of natural resource management into institutional and organizational analysis. The framework features the instrumentality of integrated institutional and organizational innovation to create opportunities and incentives to small-scale farmers to encourage investment in natural resource management practices. [ABSTRACT FROM AUTHOR]

The Soil and Water Assessment Tool ( SWAT) model (Arnold et al., 1998) is a popular watershed management tool. Currently, the SWAT model, actively supported by the U.S. Department of Agriculture and Texas A&M, operates only on Microsoft® Windows, which hinders modelers that use other operating systems ( OS). This technical note introduces the Comprehensive R Archive Network ( CRAN) distributed ' SWATmodel' package which allows SWAT 2005 and 2012 to be widely distributed and run as a linear model-like function on multiple OS and processor platforms. This allows researchers anywhere in the world using virtually any OS to run SWAT. In addition to simplifying the use of SWAT across computational platforms, the SWATmodel package allows SWAT modelers to utilize the analytical capabilities, statistical libraries, modeling tools, and programming flexibility inherent to R. The software allows watershed modelers to develop a simple hydrological watershed model conceptualization of the SWAT model and to obtain a first approximation of the minimum expected results a more complicated model should deliver. As a proof of concept, we test the SWAT model by initializing and calibrating 314 U.S. Geological Survey stream gages in the Chesapeake Bay watershed and present the results. [ABSTRACT FROM AUTHOR]

Watershed responses are affected by the watershed characteristics and rainfall events. The characteristics of soil layers are among the fundamental characteristics of a watershed and they are input to hydrologic modeling similar to topography and land use/cover. Although the roles of soils have been perceived, there are limited studies that quantify the role of soil characteristics on watershed runoff responses due to the lack of field datasets. Using two adjacent watersheds (Ribb and Gumara) which have a significant different runoff response with a similar characterstics except geological settings (including soil characteristics), we studied the effects of soil characteristics on runoff and water balance. The Soil and Water Assessment Tool (SWAT) was used to simulate the surface runoff response at the outlet of the watershed and the optimal model parameters distribution was tested with a non-parametric test for similarity. Results indicated that SWAT model captured the observed flow very well with a Nash-Sutcliffe Efficiency (NSE) of greater than 0.74 and with a PBIAS of less than 10% for both calibration and validation period. The comparison of the optimal model parameter distributions of the SWAT model showed that the watershed characteristics could be uniquely defined and represented by a hydrologic model due to the differences in the soils. Using field observations and modeling experiments, this study demonstrates how sensitive watershed hydrology is to soils, emphasizing the importance of accurate soil information in hydrological modeling. We conclude that due emphasis should be given to soil information in hydrologic analysis. [ABSTRACT FROM AUTHOR]

This article assesses the impact of the tensiometer on the consumption of groundwater and electric power in paddy cultivation in Indian Punjab, and its subsequent economic benefits. We find that compared to the continuous flooding method, the tensiometer-based application of irrigation reduces water and power consumption by 13%, cutting variable costs by 7% without any yield penalty. If 30% of the paddy area is irrigated following tensiometer-based schedules, then the state could save a total of 0.67 million ha m of water and 1516 million kWh of electric power in 2010-2025, with aggregate economic benefits of US$ 459 million. [ABSTRACT FROM AUTHOR]

In many developing countries and remote areas of important ecosystems, good quality precipitation data are neither available nor readily accessible. Satellite observations and processing algorithms are being extensively used to produce satellite rainfall products (SREs). Nevertheless, these products are prone to systematic errors and need extensive validation before to be usable for streamflow simulations. In this study, we investigated and corrected the bias of Multi-Sensor Precipitation Estimate–Geostationary (MPEG) data. The corrected MPEG dataset was used as input to a semi-distributed hydrological model Hydrologiska Byråns Vattenbalansavdelning (HBV) for simulation of discharge of the Gilgel Abay and Gumara watersheds in the Upper Blue Nile basin, Ethiopia. The result indicated that the MPEG satellite rainfall captured 81% and 78% of the gauged rainfall variability with a consistent bias of underestimating the gauged rainfall by 60%. A linear bias correction applied significantly reduced the bias while maintaining the coefficient of correlation. The simulated flow using bias corrected MPEG SRE resulted in a simulated flow comparable to the gauge rainfall for both watersheds. The study indicated the potential of MPEG SRE in water budget studies after applying a linear bias correction. [ABSTRACT FROM AUTHOR]