• Energy Research

This report describes the results of the study on options for changing the eco-nomic incentive structure for groundwater extraction in Yemen. The study aims to evaluate the potential role of economic incentives to reduce unsustainable ir-rigation water consumption and to make recommendations for implementing water conservation incentives. It first identifies factors that have triggered groundwater overdraft, then studies farmers' behaviour regarding groundwater extraction on the basis of in-depth interviews with farmers in each of the follow-ing three basins - in the Sana'a Basin, the Taiz Basin and Wadi Hadramout. Fi-nally, a number of changes in the incentive structure are evaluated, among others incentives that decrease the profitability of irrigation water use and sub-sidies on improved irrigation technology. The study shows that although the lit-erature and economic theory suggest that the range of possible interventions is wide (water pricing, metering, water rights, water markets, taxes, subsidies, in-formation, participatory management, et cetera), the range of potentially effec-tive interventions in the Yemeni political context is more limited. The Yemeni case is unique, as there is a close linkage between water and a central socio-economic issue: qat. This adds to the difficulties of implementing or enforcing change.

One of the main manifestations of climate change will be increased rainfall variability. How to deal with this in agriculture will be a major societal challenge. In this paper we explore flexibility in land use, through deliberate seasonal adjustments in cropped area, as a specific strategy for coping with rainfall variability. Such adjustments are not incorporated in hydro-meteorological crop models commonly used for food security analyses. Our paper contributes to the literature by making a comprehensive model assessment of inter-annual variability in crop production, including both variations in crop yield and cropped area. The Ganges basin is used as a case study. First, we assessed the contribution of cropped area variability to overall variability in rice and wheat production by applying hierarchical partitioning on time-series of agricultural statistics. We then introduced cropped area as an endogenous decision variable in a hydro-economic optimization model (WaterWise), coupled to a hydrology-vegetation model (LPJmL), and analyzed to what extent its performance in the estimation of inter-annual variability in crop production improved. From the statistics, we found that in the period 1999-2009 seasonal adjustment in cropped area can explain almost 50% of variability in wheat production and 40% of variability in rice production in the Indian part of the Ganges basin. Our improved model was well capable of mimicking existing variability at different spatial aggregation levels, especially for wheat. The value of flexibility, i.e. the foregone costs of choosing not to crop in years when water is scarce, was quantified at 4% of gross margin of wheat in the Indian part of the Ganges basin and as high as 34% of gross margin of wheat in the drought-prone state of Rajasthan. We argue that flexibility in land use is an important coping strategy to rainfall variability in water stressed regions.

The drought prone North-West Bangladesh is vulnerable to the impacts of climate change, particularly because of less water availability in the dry period and high water requirement for crop production. Improved understanding of recent changes in crop water demand in the dry season is important for the water resources management in the region. A study was carried out to determine the potential impacts of recent climate change during last three decades on trends of water requirements of Boro rice. The reference crop evapotranspiration (ETo), potential crop water requirement (∑ETC), effective rainfall during the crop growing period (ER), potential irrigation requirement for crop evapotranspiration (∑ETC − ER) and net irrigation requirement of Boro rice were estimated using observed daily climate data in the CropWat model for the period of 1980 to 2013 for four North-West districts. Significant decreasing trends of ETo were observed in most of the dry months due to increasing relative humidity and decreasing wind-speed and sun-shine hours. The results showed decreasing trends of potential crop water requirement, i.e. the total crop evapotranspiration (∑ETC), of Boro rice due to decreasing reference crop evapotranspiration and shorter crop growing periods. The variations in trends of potential irrigation requirement for crop evapotranspiration (∑ETC − ER) found among different districts, are mainly linked to variations in trends of changes in effective rainfall. The net irrigation requirement of Boro rice has decreased, by 11% during the last three decades at an average rate of −4.4 mm year−1, instead of decreasing effective rainfall, mainly because of high rate of decrease of crop evapotranspiration (−5.9 mm year−1). Results indicate that a warming climate does not always result in higher agricultural water use and that climate change can also result in reduced water demands because of changes in humidity, wind-speed and sun-shine hours.

This paper analyses the different impacts that biofuel production will have on water use and availability.

This study used crop budgets to assess the impact of declining groundwater levels on the economic value of irrigation water in the Wadi Zabid region of Yemen. The study found that returns to land and water were highly sensitive to changes in groundwater depths over time and the free availability of spate water for irrigation. Crops differed in the amounts of irrigation water applied and in their returns to land and water. Banana had the highest irrigation requirement, but also delivered the highest return to land. Banana’s return to water was greater than that of date palm and feed sorghum, but lower than that of mango and food sorghum.

A dense dike system has been built in the upstream floodplains of the Vietnamese Mekong Delta, allowing large scale rice production based on compartmentalized fields and optimized water management. Intensive cultivation has enabled farmers to greatly increase their rice productivity and augment the national food bowl. However, flood-control structures have undermined the water retention capacity, compromising various benefits of floodwaters for delta ecosystems. Effects are both internal and external to farming. Negative internal effects are the large investment requirements and higher farming costs. Negative externalities include increased flood damage, reduced sediment flows, saltwater intrusion and riverbank erosion. In this study, we assessed the effects of three dike–agricultural system scenarios on delta-level sustainability, considering both internal and external effects. Direct and indirect costs were estimated using various methodologies and the literature. Our findings show that extensive development of high dikes on the floodplains is the least economical and most ecologically risky alternative. In this scenario, accelerated high-dike construction exacted a cost 136% greater than the situation represented by the baseline year of 2011. Externalities in this scenario contributed to rising economic losses in both aquaculture and agriculture. The scenario of transforming high-dike into low-dike systems revealed lower water management costs combined with lesser environmental impacts and greater capacity to exploit floodwater benefits. Our findings provide a useful input for decision-makers considering the unintended economic consequences of existing water management strategies. They support a transition to low-dike farming systems for a more sustainable delta.