Land-Use and Land-Cover (LULC) Change Detection and the Implications for Coastal Water Resource Management in the Wami–Ruvu Basin, Tanzania

Abstract

Evaluation of river basins requires land-use and land-cover (LULC) change detection to determine hydrological and ecological conditions for sustainable use of their resources. This study assessed LULC changes over 28 years (1990–2018) in the Wami–Ruvu Basin, located in Tanzania, Africa. Six pairs of images acquired using Landsat 5 TM and 8 OLI sensors in 1990 and 2018, respectively, were mosaicked into a single composite image of the basin. A supervised classification using the Neural Network classifier and training data was used to create LULC maps for 1990 and 2018, and targeted the following eight classes of agriculture, forest, grassland, bushland, built-up, bare soil, water, and wetland. The results show that over the past three decades, water and wetland areas have decreased by 0.3%, forest areas by 15.4%, and grassland by 6.7%, while agricultural, bushland, bare soil, and the built-up areas have increased by 11.6%, 8.2%, 1.6%, and 0.8%, respectively. LULC transformations were assessed with water discharge, precipitation, and temperature, and the population from 1990 to 2018. The results revealed decreases in precipitation, water discharge by 4130 m3, temperature rise by 1 °C, and an increase in population from 5.4 to 10 million. For proper management of water-resources, we propose three strategies for water-use efficiency-techniques, a review legal frameworks, and time-based LULC monitoring. This study provides a reference for water resources sustainability for other countries with basins threatened by LULC changes.

Socio-ecological change in the Ruvu Estuary in Tanzania, inferred from land-use and land-cover (LULC) analysis and estuarine fisheries

“…These overall findings agree with a larger LULC study of the WRB (Ngondo et al, 2021) and are related to water resource implications. Since 1990, coastal populations have increased significantly with related demands for agricultural products and water, resulting in the conversion of wetlands to cultivated lands.…”

“…Rainfall (900 to 1300 mm p/a; GLOWS-FIU, 2014a) occurs in March-May and October-December, FIU, 2014b;2014c). Upstream of the estuary, the Ruvu River flows through major agricultural, industrial, and urban areas where freshwater is diverted for irrigation, industrial, aquaculture and domestic use (Ngondo et al, 2021). With rapid coastal expansion, particularly at Dar es Salaam where there is a critical water supply/ demand deficit, the WRB is of high strategic importance and has been the subject of numerous impact assessments, predictive models, policy documents and published research (e.g., GLOWS-FIU, 2014ad;van Eeden et al, 2016;Mdee, 2017;Alphayo and Sharma, 2018;Miraji et al, 2019;Ngondo et al, 2021).…”

“…Seasonal and decadal changes in land-use and landcover (LULC) are good indicators of socio-ecological interactions, because they provide information on hydrological and ecological conditions that govern natural capital use (e.g., Ngondo et al, 2021;Taylor and Suthers, 2021). The aims of this study…”

Quantitatively Assessing the Future Land-Use/Land-Cover Changes and Their Driving Factors in the Upper Stream of the Awash River Based on the CA–Markov Model and Their Implications for Water Resources Management

“…Similarly, the study reported by [139] showed that LULC changes are one of the key drivers of hydrological changes in the watershed. LULC change is a complex source of pressure that threatens the sustainability and management of water resources [136,140]. The impact of the LULC change pattern on the sub-basins connecting coastal areas and highland areas has led to economic, social, political, and environmental problems at the national, regional, and local levels in many countries.…”

Exploring urbanization and critical habitat loss through land cover change around the Bons Sinais Estuary, Mozambique

“…Furthermore, the estuary provides nutrients that nourish adjacent coastal marine ecosystems and nurseries (Hoguane and Armando, 2015) and the dense mangrove forests are an important carbon sink and mitigation against climate change (Amade et al, 2019). Remote sensing and GIS techniques are often applied to detect change in LU and LC by season or over longer time frames (Mallupattu and Reddy, 2013;Berlanga-Robles and Ruiz-Luna, 2002;Hudak and Wessman, 1998;Ngondo et al, 2021). Analysis of satellite images is a cost-effective means of mapping physiognomic habitats, including mangroves, wetlands, sand and seagrass beds and coastline morphology (Dittrich et al, 2020;Dymond et al, 2019;Marzialetti et al, 2019).…”