Impact of land use on water quality in the Likangala catchment, southern Malawi

Abstract

Safe drinking water, good sanitation and hygiene are important for good health, human survival and development. However, human activities have affected water quality in many river catchments worldwide. Hellar-Kihampa et al. (2013) concluded that the Pangani River, Tanzania, had the worst water quality in the Moshi, Arusha and Kilimanjaro region, with the highest levels of Na + , K + , Mg 2+ , HCO 3 − and F − , the presence of these contaminants being as a result of human activities. Industrial water pollution has also been reported in many countries in Africa such as Lesotho (Pullanikkatil and Urama 2011) and Ghana (Attua et al. 2014). Changes in water quality are usually associated with changes in land use (Arnold and Gibbons 1996). Characterising changes in land use, coupled with increased population growth, has revealed the vulnerability of water quality in various catchments. The clearing of natural vegetation and the transformation of natural land use into urban developments are known to increase runoff and sediment loads, which also facilitates the transfer of pollutants from land to waterbodies (Arnold and Gibbons 1996). A positive correlation between population density and deterioration in water quality was found along the Bagmati River, Nepal (Bhatt et al. 2014). Therefore, combined pressures of human population growth, inadequate treatment of human wastes and ineffectively managed and treated industrial and agricultural wastes make it imperative that continuous monitoring of water quality is implemented for the provision of clean and safe water for human consumption and optimal environmental integrity. Africa's water resources are underutilised and pollution of both surface and groundwater resources has been increasing, leading to serious health risks to both humans and the ecosystem (UNECA u.d.). Pollution has caused the growth of water hyacinth which has affected, for example, Lake Victoria, the Nile River, and Lake Chivero in Zimbabwe. Malawi's river catchments, in spite of being important for its population, have been deteriorating in terms of river channel integrity, ecosystem health and water quality due to human activities. The Likangala River catchment, southern Malawi, which includes forest reserves, is affected by changes in land use caused by the increasing population and breakdown in catchment management and conservation practices. Deforestation, agriculture and degrading activities such as waste disposal, river bank cultivation and river sand mining have affected the water quality of this river (Jamu et al. 2003; Chavula and Mulwafu 2007). Chidya et al. (2011) assessed the quality of water in the Likangala River and showed that it is affected by pollution from human activities. The present study updates and expands that study, focusing on water quality, and observes land use with the intent of identifying the major land-based activities that cause changes in water quality. Study area The Likangala River is the only river in Malawi that passes through a city (Zomba) and its catchment include...

Assessment of Water Quality Across Irrigation Schemes: A Case Study of Wetland Agriculture Impacts in Kilombero Valley, Tanzania

“…Ammonium-N and Nitrate-N naturally occur in water bodies as a result of the breakdown of organic and inorganic matter in water, excretion from biota and reduction of atmospheric nitrogen by microorganisms [52,53]. However, the application of fertiliser in the irrigated rice and vegetable farms downstream could explain the relatively high level of nutrients at these particular sites [5,10,54]. Decomposition of nitrogen-containing organic compounds such as plants and crops residuals is another potential source of contamination in the area, which could explain lower mean DO values downstream irrigation.…”

Landuse and surface water quality in an emerging urban city

“…The three parameters (TS, TDS, and TSS) to a greater extent evaluate the quality of a drinking water, and their violation limits the aesthetic value of the water by increasing its turbidity which in a way becomes a public health issue (Mendie 2005;Ayeni et al 2006). Some studies have indicated high turbidity in urban areas (Pullanikkatil et al 2015) and in areas where sewage is discharged into waterways (Mendie 2005). Furthermore, the high values of TS and TDS across the landuse could be attributed to various sociocultural factors such as indecent disposal of household water into water channels, excessive use of fertilizers from farming activities on floodplains and unchecked effluents discharged directly into water bodies.…”

“…The studied river flows into a reservoir downstream; hence, the values as observed across the three landuse types are way beyond the permissible limit. Anthropogenic activities are the main contributors of excessive PO 4 into river channels; sewage discharge, runoff from agricultural sites, and the release of detergent during domestic washing especially along river channel sections are common practices (Saksena et al 2008;Pullanikkatil et al 2015). The load contribution of detergents raises the level of phosphate in water channels due to the weight of inorganic condensed phosphates (Usharani et al 2010).…”

“…In recent years, there has been a rapid declining availability of usable fresh water in terms of water quality and quantity due to unsustainable landuse practices (Ngoye and Machiwa 2004). Water quality has variously been related to landuse in catchment (Levin 2012;Faiilagi 2015;Henderson et al 2014;Li et al 2008;Ayeni et al 2006;Pullanikkatil et al 2015;Wagner et al 2013;Olusola et al 2018), and studies have been focusing on their relationships with water quality variables such as dissolved salts, suspended solid, and nutrients (Mallin 2008;Mathuthu et al 1997;Elbag 2006;Keshtkar et al 2010;Olusola et al 2017). However, Pullanikkatil et al (2015) argued that there are correlations between systems of landuse and water quality, and emphasized the use of water quality index (WQI) in identifying pollution hot spots.…”

“…Water quality has variously been related to landuse in catchment (Levin 2012;Faiilagi 2015;Henderson et al 2014;Li et al 2008;Ayeni et al 2006;Pullanikkatil et al 2015;Wagner et al 2013;Olusola et al 2018), and studies have been focusing on their relationships with water quality variables such as dissolved salts, suspended solid, and nutrients (Mallin 2008;Mathuthu et al 1997;Elbag 2006;Keshtkar et al 2010;Olusola et al 2017). However, Pullanikkatil et al (2015) argued that there are correlations between systems of landuse and water quality, and emphasized the use of water quality index (WQI) in identifying pollution hot spots. Rapid socioeconomic advancement drives landuse change (Wagner et al 2013) as evident in cases where deforestation, agricultural activities and urbanization, individually or collectively, modify land surface characteristics, alter runoff volume, change water temperature, generate pollution, increase algal production and decrease concentration of dissolved oxygen in water bodies (Irenosen et al 2012;Jiao et al 2015;Adediji and Fashae 2014;Olusola et al 2018).…”