Changes in Streamflow Statistics and Catchment Land Uses Across Select USGS Gages in Northwest and West-central Arkansas

Since 1901, heavy rainfall events have increased in the United States in both intensity and frequency, and human population in the United States has increased, resulting in significant land use changes. Both trends contribute to an increase in observed flood magnitude and frequency. To determine if a relationship exists between land use/land cover and changing stream flows in northwest Arkansas, this study analyzed temporal changes in various flow statistics for 14 stream gages and compared the rates of change in flow statistics from gages on streams with watersheds that have varying land uses, i.e., urban, agricultural, and undeveloped. Mann-Kendall analysis was used to determine statistically significant changes in flow statistics, which were then compared to National Land Cover Dataset (NLCD) watershed land uses from 2001 and 2019. All analyzed gages had one or more flow statistics with at least a moderately significant increase, and all analyzed flow statistics showed at least moderately significant streamflow increases at two or more gages (P < 0.100). There were no decreases of any significance in any flow statistic at any gage. In general, urban land development did not happen on native prairies and forests but on previously agricultural land. Significant positive relationships were found between maximum yearly flow and 2019 urban land use, urban land use change from 2001 to 2019, and 2019 Human Development Index (HDI). A similar relationship was found to exist between yearly minimum flow and 2019 HDI. These results highlight the importance of considering the cost of potential stream bank erosion and flooding in future land use planning, permitting, and zoning.