NONPARAMETRIC ANALYSIS OF CHANGES OF HEAVY PRECIPITATION IN TEXAS
The county-by-county approach permits analysis of county-scale variations in extreme rainfall trends. These county-scale variations are interpreted as random variations in the extreme precipitation records, and are larger in southern and western Texas than in northern and eastern Texas. The large variations indicate that local historical records of floods are not reliable for inferring robust long-term trends. For example, Houston has seen many damaging floods over recent years, but the change in precipitation extremes in Harris County, where Houston is located, is exceptionally large compared to surrounding counties and is unlikely to continue apace.
Extreme daily rainfall events can be damaging, but the runoff from extreme events is often essential for replenishment of surface water resources during times of drought. Thus these trends have both positive and negative implications for Texas society. The observed rates of increase are consistent with the amount expected from an increase in atmospheric temperatures and from climate model projections, suggesting that the larger-scale historical changes are likely to continue.