Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 1999
Publication Date: October 1, 1999
Citation: BOSCH, D.D., SHERIDAN, J.M., DAVIS, F.M. RAINFALL CHARACTERISTICS AND SPATIAL CORRELATION FOR THE UNITED STATES SOUTHERN COASTAL PLAIN. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 42(6):1637-1644. 1999. Interpretive Summary: Rainfall is a key factor in shaping vegetation, hydrology, and water quality throughout the earth. As additional insight into farming practices is gained, the importance of rainfall variability becomes more apparent. Soil-water content is consistently found to be one of the most important factors affecting crop yield. An accurate understanding of precipitation characteristics and soil variability is critical to optimizing farm production. Thirty years of rainfall data from the Little River Watershed near Tifton, GA have been analyzed. We found that summer storms are more intense, shorter, yield less rainfall, and occure more frequently. These storms were also found to be highly variable, particularly during the summer. Throughout much of the year, good quality estimates of rainfall can be obtained from raingages spaced as far apart as 5 km. The accuracy of these estimates can be improved by placing these raingages parallel to the primary direction of storm travel. These data will be useful in planning planting times and agrichemical management. The data also provide guidelines for establishing meaningful precipitation measurement networks.
Technical Abstract: The southern Coastal Plain of the U.S. holds significant agricultural and hydrologic importance. Profitability and sustainability of agriculture in this and other regions are dependent upon climatic patterns, particularly rainfall. Developing an understanding and characterizations of seasonal and individual storm characteristics is critical. Thirty years of rainfall ldata collected from a dense raingage network on the Little River Watershed near Tifton, GA were analyzed for this purpose. Storm patterns were characterized by season in order to establish mean behaviors and trends. Individual storm characteristics and spatial correlation patterns within storms were quantified. Rainfall patterns, although highly variable from year to year, show rainfall to be greatest in midsummer months. While these summer storms yield relatively low rainfall depths, they occur more frequently than during other seasons. Fall months generally have low rainfall totals and storms during this season occur less frequently. For the larger storm events, defined here as those where at least one raingage in the network measured 25.4 mm or greater during the event, the mean storm depth weighted over the storm coverage was 20.6 mm and the mean storm duration was 7.2 hrs. For these larger events, summer storms are separated by the least time between events while the fall events are separated by the greatest time. For summer events, raingage depths for individual storm events collected by gages separated by 1.9 km or less are likely to be highly correlated. This distance increases to 9.2 km for the winter. High correlations are expected up to distances of 5 km throughout most of the year, except summer.