Impacts of Land-Use Change, Associated Land-Use Area and Runoff on Watershed Sediment Yield: Implications from the Kaduna Watershed

Abstract

An uncontrolled sediment influx from the watershed upstream is a known threat to dam stability, while the pattern and amount of sediment yield are influenced by the predominant upstream land-use and land cover (LULC) types, precipitation amount, and intensity. Hence, the need to monitor sediment yield accumulation and its controlling factors in dam operation becomes crucial. In this paper, the Soil and Water Assessment Tool (SWAT) was used to assess the roles of land-use change, land cover area, and runoff on watershed’s sediment yield based on change detection analysis between 1975 and 2013 in the Kaduna Watershed (Nigeria), Western Africa. The SWAT standard procedures for the simulation of hydrological characteristics and sediment yields prediction were adopted. The datasets were calibrated for a period of 46 years and validated using 2015–2017 measured flow data, and suspended sediments concentration (SSC) acquired between March and October 2018. The model function was statistically determined using the Nash-Sutcliffe (NS), the coefficient of determination (r2) and the percentage of observed data (p-factor). The evaluation results of the SWAT model yielded NS, r2 and p-factor of 0.71, 0.80, and 0.86, respectively. These data suggest that the model performed satisfactorily for streamflow and sediment yield predictions. Findings suggest that the extinction of evergreen forests and a significant change in land-use from range grasses and forest to agriculture generic and residential types between 1975 and 2013, which resulted in surface runoff, sediment yield, and flow alteration. Evapotranspiration increased by 22.40% between 1975 and 2013. These changes have negatively impacted the watershed runoff by 56.00% and model sediment yield by 68.00% at the end of 2013. Thus, these variations can influence various human activities in the watershed, such as food security, livestock, energy production and water supply. It is hypothesized from the presented data that land use types exact a more dominant control on runoff and sediment yield than land cover area, although climatic influence may not be ruled out.

Impacts of Climatic Variation on Water Balance and Yield of Watershed (Insights from The Kaduna Watershed, North Central Nigeria)

“…The watershed hydrological processes were quantified using the SWAT model (Table 5); the analysis result revealed that precipitation has continued to decrease since 1975 to about 4.2% in 2013. The prediction agrees with Daramola et al, 2022;Bello et al, 2012;Mohammed, 2014;Odjugo, 2005;Ogilvie et al, 2010;Nicholson, 2013;Idowu et al, 2011;Fasona and Omojola, 2005;Mahé and Olivry, 1999;Abaje et al, 2010;Mahe et al, 2013). Similarly, Aigbe and Oluku (2012) connected the extinction of forest cover in Nigeria to a constant reduction in rainfall.…”

“…Abbaspour et al, (2015) explained that these uncertainties are expected in a large watershed. Thus, a large watershed as large as the Kaduna watershed will experience all these uncertainties that may be largely responsible for the high r-factor prediction (Daramola et al, 2022). However, the general statistical evaluation performance of the model using Nash-Sutcliff, coefficient of determination, p-factor, and r-factor shows that the prediction is within the suitable standards (Moriasi et al, 2007;Krause et al, 2005;Motovilov et al, 1999).…”

“…The main factor responsible for high evaporation experience in the region is attributed to the high ratio of bare soils (Brouziyne et al, 2018). (Daramola et al, 2022) identified rangeland use class in the study area to consist of the steppe, i.e., an open intermittent herbaceous ground cover, occasionally mixed with shrubs and trees with inadequate cover to withstand severe weather anthropogenic activities. This might be one of the main contributions of the high percentage rate of evaporation in the water balance of the study basin.…”

“…Largely, human anthropogenic activities, most especially land-use change, are responsible for climate variation in Nigeria (Sule and Odekunle, 2016;Bello et al, 2012;Fasona and Omojola, 2005;Idowu et al, 2011;Nicholson, 2013). Existing literature revealed the impacts of climate variation in different parts of Nigeria, including the decline in cultivated, savanna, and riparian areas Daramola et.al., 2022;Daramola et.al., 2020;Fasona and Omojola, 2005;Nzoiwu et al, 2017;Idowu et al, 2011), increased surface radiant temperature (Daramola et al, 2022;Bello et al, 2012;Nzoiwu et al, 2017;Ogilvie et al, 2010), unpredictable rainfall and rainfall decline, irregular runoff and sunshine hours (Daramola et.al., 2022) (Mahe et al, 2013) (Mohammed, 2014) (Nicholson, 2013) (Abaje et al, 2010) (Idowu et al, 2011) (Odjugo, 2005) (Mahé and Olivry, 1999), drought and flood (Douglas et al, 2008;Idowu et al, 2011;Odjugo, 2005;Odemerho, 2015), water shortages in reservoirs, rivers, irrigation for agriculture and industrial usage (Ishaku and Majid, 2010), and increase in air temperature (Bello et al, 2012). Adams and Peck (2008) stated that climate change impacts on the hydrologic cycle are very important and have led to a decline in annual average runoff, reduction of available freshwater, surged evaporation rates and rainfall variability.…”

Assessment of landuse/landcover dynamics of Kaduna watershed, using remote sensing data and GIS techniques

“…The combination of GIS tools and remote sensing have led to a new model in environmental studies (Chukwudi et al, 2017). Remote sensing and GIS have been extensively accepted in environmental resources management and widely applied in landuse and landcover change detection (Overmars et al, 2007;Pontius et al, 2001;Mas et al, 2014) and land classifications as well (Feranec, 2000;Lambin, 1997;Heymann, 1994;Ahmed et al, 2018;Daramola et al, 2022).…”