Spatiotemporal trend analysis of precipitation, temperature, and soil moisture in selected agrarian locations within Nigeria—a comparative study

Abstract

Changes in trends and variabilities of precipitation, temperature, and evaporation are some of the pronounced effects of climate change. This study assessed the effects of precipitation and temperature trends and variabilities on soil moisture storage. Forty-one years’ historical data on precipitation, temperature, and soil moisture were collected for four agrarian local government areas in southern and northern Nigeria. Trend changes and variabilities were analyzed using the Mann Kendall, modified Mann Kendall, Palmer drought severity index, standardized precipitation evaporation index, standardized precipitation index, and temperature indices. Observed precipitation in the northern part experienced very significant decrease and both the southern and northern divides experienced significant temperature increase over the last four decades. However, the temperature indices including hottest days (TXx), summer day (SU35), and diurnal temperature range (DTR) indicated northern Nigeria experienced more extreme temperature increase and thus more drought than southern Nigeria. The northern part had averages TXx, SU35, and DTR of 39.66 °C, 66.49 days, and 17.99 °C, while the southern part had 33.61 °C, 0.075 days, and 9.47 °C, respectively. The continuous increase in temperature and precipitation decrease are attributable to climate change caused by ozone layer depletion. Low precipitation and high temperature resulted to significant reduction of soil moisture storage in northern Nigeria, while soil moisture reductions were limited in southern Nigeria. Effects of temperature and precipitation trends on soil moisture trends therefore emphasize the need for proper water management, continuous soil moisture conservation, and intense irrigation practices, to enhance food production and security.