H ydrologic extremes are costly to the nation. Annual U.S. drought and flood damages over the last decade have averaged between $6–$8 and $2 billion, respectively (FEMA 1995). Losses associated with the four-year 2000s drought in the western United States are likely to be in the tens of billions of dollars. To the extent that floods and droughts can be mitigated by management of water stored in...

Tree-ring data from Virginia indicate that the Lost Colony of Roanoke Island disappeared during the most extreme drought in 800 years (1587-1589) and that the alarming mortality and the near abandonment of Jamestown Colony occurred during the driest 7-year episode in 770 years (1606-1612). These extraordinary droughts can now be implicated in the fate of the Lost Colony and in the appalling dea...

Introduction The Islamic Republic of Iran (Figure 1) has an area of 1,648,000 km 2 and a population of 65 million people (1995 estimate). The country has arid and semiarid climates and the occurrence of rainfall is unreliable, with a coefficient of variation as high as 70%. The average annual precipitation over the country is around 250 mm. Two mountain ridges, the Alborz and Zagros (Figure 1),...

there are different materials and compounds in water that determine its chemical and physical quality. as the result of special conditions such as increase and decrease in discharge, water quality can vary. one of these conditions is drought that decreases discharge, and water quality changes. in this study, droughts of sistan and baluchistan province have been analyzed using standardized preci...

– Use of logarithmic function for drought severity assessment. Due to the multiplicative and cumulative effect of various risk events, the use of logarithmic function can provide satisfactory results in the analysis of risks. Based on the monthly values of climatic parameters from fourteen stations in the eastern part of Romania (1961-2006), the author uses the logarithmic function to evaluate ...

The 132-year historical rainfall record reveals that severe droughts in India have always been accompanied by El Niño events. Yet El Niño events have not always produced severe droughts. We show that El Niño events with the warmest sea surface temperature (SST) anomalies in the central equatorial Pacific are more effective in focusing drought-producing subsidence over India than events with the...

Southern California and much of the western United States face a chronic challenge of limited water supply due to high potential evaporation and low precipitation coupled with frequent droughts. Mitigation approaches include the use of ground water, reliance on water from river systems fed by mountainous regions that have relatively high precipitation, and the construction of extensive aqueduct...

Droughts can be characterized by their severity, frequency and duration, and areal extent. Depth-area-duration analysis, widely used to characterize precipitation extremes, provides a basis for evaluation of drought severity when storm depth is replaced by an appropriate measure of drought severity. We used gridded precipitation and temperature data to force a physically-based macroscale hydrol...

-Extreme hydrologic disturbance, such as a supraseasonal drought, can dramatically influence aquatic communities. Documentation of the responses of aquatic communities after such disturbances provides insight into the timing, order, and mechanisms of recolonization. Postdisturbance recolonization of streams depends on many factors, including the region and characteristics of the disturbance rel...