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In flat plains groundwater affects agricultural production outcomes and risks. Agricultural land use decisions, however, may strongly impact groundwater levels available for production. This paper explores the scope for managing groundwater levels through land use decisions in a sub-basin of the Salado River in the Argentine Pampas, a very flat area that plays a key role in world agricultural production. A spatially distributed hydrological model implemented with MIKE SHE software was used to establish the impacts of different land uses on groundwater dynamics, and to assess the interdependencies among spatially close decision-makers sharing a water table (WT). Additionally, groundwater level changes in response to climate variability were quantified. We found land use has strong effects on WT levels both for oneself (e.g. pastures can lead to significant decreases (up to 4.5 m) in WT levels) and others, in the form of strong interdependencies that exist between farmers sharing a WT where land use decisions of one farmer effect groundwater level of neighbouring farms and vice versa. However, the effectiveness to control groundwater levels through land use decisions is subject to the rather unpredictable effects of rainfall variability. The results presented in this paper provide key insights in relation to physical and social aspects that should be considered for managing groundwater levels through land use decisions, in order to avoid negative and/or maximize positive effects on agricultural production. [ABSTRACT FROM PUBLISHER]

The objective of this paper is to analyse, for the Senegal River basin, the evolution of four classes of daily precipitation, the number of rainy days and the duration of the rainy season. The approach is to apply statistical tests of homogeneity to the series of annual rainfall over the period 1950–1998 to detect abrupt changes and to characterize the evolution of these six variables on each side of the change dates. The time series present an abrupt change (break) between 1966 and 1970. Deficits of rainy days in the period after the break compared to before vary between 6.2% at Kédougou and 38.6% at Saint Louis. The class of rain of more than 50 mm (P4) has the largest deficit, ranging from 14.8% at Mamou station to 66.6% at Nioro du Sahel.Editeur Z. W. Kundzewicz; Edithur Associé E. Gargouri [ABSTRACT FROM AUTHOR]

This paper quantifies the impacts of bushfire and climate variability on streamflow from three southeast Australian catchments where bushfires occurred in February 1983. Three hydrological models (AWRA-L, Xinanjiang and GR4J) were first calibrated against streamflow data from the pre-bushfire period and then used to simulate runoff for the post-bushfire period with the calibrated parameters. The difference in simulated streamflow between pre- and post-bushfire periods provides an estimate of the impact of climate variability on streamflow. The impact of bushfire on streamflow is quantified by removing the climate variability impact from the difference in mean annual observed streamflow between post- and pre-bushfire periods. For the first 15 years after the 1983 bushfires, the results from hydrological models for the three catchments indicate that there is a substantial increase in streamflow; this is attributed to initial decreases in evapotranspiration and soil infiltration rates resulting from the fires, followed by logging activity. After 15 years, streamflow dynamics are more heavily influenced by climate effects, although some impact from fire and logging regeneration may still occur. The results show that hydrological models provide reasonably consistent estimates of bushfire and climate impacts on streamflow for the three catchments. The models can be used to quantify relative contributions of forest disturbance (bushfire, logging and other forest management) and climate variability. The results presented can also help forest managers understand the relationship between bushfire and climate variability impacts on water yield in the context of climate variability. [ABSTRACT FROM AUTHOR]