Keywords
spatial variability, rainfall, modeling, semiarid
Start Date
1-7-2006 12:00 AM
Abstract
In this paper the main goal was to analyze the effect of spatial variability of rainfall on runoff in an experimental monitored watershed (2.108 km2) located on a semiarid region (Seridó Potiguar), Rio Grande do Norte-Brazil. To accomplish this, a rainfall-runoff-sediment hydrologic model was used. The study area was divided into 143 elements (planes and channels). Rainfall spatial distribution, estimated using the inverse of distance method, was used as input to calculate rainfall spatial variability index for three observed storm events and different combinations of recording gauge arrangements. This index was considered in this study as an indicator used to evaluate the capacity of rainfall spatial characteristics measurement. The impact of spatial rainfall variability on catchment hydrologic response was analyzed and permitted to obtain the following conclusions: (a) rainfall data input provided by gage combination [1-2] best described rainfall distribution, although station 1 is located far from the outlet section. It confirmed that raingage spatial arrangement affects rainfall description capacity; (b) rainfall data input provided by combinations containing gage 3 poorly described rainfall distribution, although it is located near the outlet section. Presumably, it seems that gage 3 is the one that is impacted by the hillslope effect on northern part of the catchment; (c) catchment response of a relatively small catchment area is quite sensitive to the occurrence of high rainfall spatial variability.
Uncertainty analysis associated with Rainfall Spatial Distribution in an Experimental Semiarid Watershed, Northeastern Brazil
In this paper the main goal was to analyze the effect of spatial variability of rainfall on runoff in an experimental monitored watershed (2.108 km2) located on a semiarid region (Seridó Potiguar), Rio Grande do Norte-Brazil. To accomplish this, a rainfall-runoff-sediment hydrologic model was used. The study area was divided into 143 elements (planes and channels). Rainfall spatial distribution, estimated using the inverse of distance method, was used as input to calculate rainfall spatial variability index for three observed storm events and different combinations of recording gauge arrangements. This index was considered in this study as an indicator used to evaluate the capacity of rainfall spatial characteristics measurement. The impact of spatial rainfall variability on catchment hydrologic response was analyzed and permitted to obtain the following conclusions: (a) rainfall data input provided by gage combination [1-2] best described rainfall distribution, although station 1 is located far from the outlet section. It confirmed that raingage spatial arrangement affects rainfall description capacity; (b) rainfall data input provided by combinations containing gage 3 poorly described rainfall distribution, although it is located near the outlet section. Presumably, it seems that gage 3 is the one that is impacted by the hillslope effect on northern part of the catchment; (c) catchment response of a relatively small catchment area is quite sensitive to the occurrence of high rainfall spatial variability.
