Abstract:Groundwater flooding occurred in the upper parts of many chalk rivers in the UK during the exceptionally wet winter of 2000-01. This provided a rare opportunity to investigate the spatial distribution of groundwater discharge and flooding along the normally dry intermittent headwaters of a chalk catchment. The extent of flooding along the River Pang, upstream of the seasonal head, was mapped using aerial photography, and point measurements of flow and water temperature were used to identify the contributing reaches of the river. The results are discussed in the context of the geological and groundwater conditions. The occurrence of flooding can largely be explained by the regional groundwater flow directions, but increased flow in some locations may be as a result of preferential groundwater flow along lines of geological structure.  Crown

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Models of varying complexity are available to provide estimates of recharge in headwater Chalk catchments. Some measure of how estimates vary between different models can help guide the choice of model for a particular application. This paper compares recharge estimates derived from four models employing input data at varying spatial resolutions for a Chalk headwater catchment (River Pang, UK) over a fouryear period (1992)(1993)(1994)(1995) that includes a range of climatic conditions. One model was validated against river flow data to provide a measure of their relative performance. Each model gave similar total recharge for the crucial winter recharge period when evaporation is low. However, the simple models produced relatively lower estimates of the summer and early autumn recharge due to the way in which processes governing recharge especially evaporation and infiltration are represented. The relative uniformity of land use, soil types and rainfall across headwater, drift-free Chalk catchments suggests that complex, distributed models offer limited benefits for recharge estimates at the catchment scale compared to simple models. Nonetheless, distributed models would be justified for studies where the pattern and amount of recharge need to be known in greater detail and to provide more reliable estimates of recharge during years with low rainfall.

Abstract. This paper presents a short summary of a report on 'Drought Events in Europe' (Bradford, 1999) commissioned by the Space Applications Institute (SAl) of the EC Joint Research Centre to identify particular drought-related topics for discussion during the workshop on 'Drought and Drought Mitigation in Europe'. This report was based on a review of recent literature on drought occurrence and extent, regional aspects of European droughts, and drought mitigation and planning, with an emphasis on hydrological droughts over the past decade. It included a brief description of common drought indices, impacts, events and mitigation measures illustrated by examples of studies on drought-related issues in Europe.

A network of benchmark catchments has been selected to improve the ability to identify and interpret hydrological trends throughout the UK. The designation of this network is examined within the context of a wider review of the gauging station network designed to address a broad range of strategic hydrological needs.