A predictive modelling tool for assessing climate, land use and hydrological change on reservoir physicochemical and biological properties

Better information on greenhouse gas (GHG) emissions and mitigation potential in the agricultural sector is necessary to manage these emissions and identify responses that are consistent with the food security and economic development priorities of countries. Critical activity data (what crops or livestock are managed in what way) are poor or lacking for many agricultural systems, especially in developing countries. In addition, the currently available methods for quantifying emissions and mitigation are often too expensive or complex or not sufficiently user friendly for widespread use.The purpose of this focus issue is to capture the state of the art in quantifying greenhouse gases from agricultural systems, with the goal of better understanding our current capabilities and near-term potential for improvement, with particular attention to quantification issues relevant to smallholders in developing countries. This work is timely in light of international discussions and negotiations around how agriculture should be included in efforts to reduce and adapt to climate change impacts, and considering that significant climate financing to developing countries in post-2012 agreements may be linked to their increased ability to identify and report GHG emissions (Murphy et al 2010, CCAFS 2011, FAO 2011).

Detecting vulnerability of humid tropical forests to multiple stressors

Greenhouse gas (GHG) emissions resulting from the Land Use, Land-Use Change, and Forestry sector (LULUCF) are estimated and reported in National Communications to the United Nations Framework Convention on Climate Change (UNFCCC). By definition, the LULUCF sector is a “greenhouse gas (GHG) inventory sector that covers emissions and removals of greenhouse gases resulting from direct human-induced land use, land-use change and forestry activities”. In principle, the annual GHG national inventory should be transparent, consistent, comparable, complete, and accurate. Also, it should be able to systematically account for all changes in land use and forest cover over many years. In this context, it is essential to investigate the development of an automated approach for mapping local GHG emissions/removals from the LULUCF sector for integration at the national level. In view of that, the aim of this work was to develop a semi-automated model for estimating GHG emissions and removals form the LULUCF sector at the local level. The specific objectives were to 1) map changes in land use and forest cover between two consecutive years, and 2) assess GHG emissions and removals from the LULUCF sector. The methodology of work comprised the use of Geographic Object-Based Image Analysis (GEOBIA) for modelling changes in the LULUCF sector and, subsequently, estimating GHG emissions/removals between two consecutive years. The combined use of Very High Resolution (VHR) SPOT imagery (2.5 m colour) and field data was involved in identifying and mapping land-use changes between 2014 and 2015. Subsequently, GHG emissions and removals were estimated using customized features in GEOBIA and following the 2003 Intergovernmental Panel on Climate Change “Good Practice Guidance for Land Use, Land-Use Change and Forestry”, which adopts a land use category-based approach to estimate emissions/removals from all land categories and all relevant GHGs. An accuracy assessment of the initial classification was conducted with the use of reference data. The overall classification accuracy of the LULUCF mapping in 2014 was found to be 83%, while the Kappa Index of Agreement (KIA) was 0.74. The developed GEOBIA model estimated for the year 2015 net annual GHG removals of -1.613 Gg of CO2 eq. (i.e., an approximate increase of 12.7% in removals between 2014 and 2015). Future work will involve further development of the model to account for all possible changes in the LULUCF sector and test the transferability of the model to other sites.

Africa depends on its water resources for hydroelectricity, inland fisheries, and water supply for domestic, industrial, and agricultural operations. Anthropogenic climate change (CC) has changed the state of these water resources. Land use and land cover has also undergone significant changes due to the need to provide resources to a growing population. Yet, the impact of the Land Use and Land Cover Change (LULCC) in addition to CC on the water resources of Africa is underexplored. Here we investigate how precipitation, evapotranspiration (ET), and river-flow respond to both CC and LULCC scenarios across the entire African continent. We set up a SWAT+ model for Africa and calibrated it using the Hydrological Mass Balance calibration (HMBC) methodology detailed in Chawanda et. al., (2020). The model was subsequently driven by an ensemble of bias-adjusted global climate models to simulate the hydrological cycle under a range of CC and LULCC scenarios. The results indicate that the Zambezi and the Congo River basins are likely to experience reduced river flows under CC by up to 7% decrease, while the Limpopo will likely have higher river flows. The Niger River basin is likely to experience the largest decrease in river flows in all of Africa due to CC. The Congo River basin has the largest difference in river flows between scenarios with (over 18%% increase) and without LULCC (over 20% decrease). The projected changes have implications on agriculture and energy sectors and hence the livelihood of people on the continent. Our results highlight the need to adopt policies to halt global greenhouse gas emissions and to combat the current trend of deforestation to avoid the high combined impact of CC and LULCC on water resources in Africa.

Climate change and land use land cover (LULC) changes are recognised as two of the most significant causes of environmental change. Climate change and LULC changes are related to one another. Land use change may drive climate change, and a changing climate may result in land cover changes. Climate change and LULC changes are believed to influence soil erosion. This chapter analyses the impacts of climate and LULC changes on soil erosion. The causes and effects of climate change on precipitation, temperature, solar radiation, atmospheric CO2 concentrations, and radiative forcing are discussed. The chapter includes the impacts of climate change on soil characteristics, vegetation cover, runoff, floods, and droughts and extends the impacts of these changes on water and wind erosion. The chapter explores the human alterations of LULC changes in terms of changes in the forest cover, alterations in agricultural lands, increase in urban areas, and decrease in wetland areas. The influence of the LULC changes on soil erosion and sediment production processes is discussed. Also, the combined impact of climate and LULC changes on soil erosion is explored, and mitigation strategies like sustainable land management practices and appropriate policy incentives to conserve soil are discussed.

Abstract. Africa depends on its water resources for hydroelectricity, inland fisheries and water supply for domestic, industrial and agricultural operations. Anthropogenic climate change (CC) has changed the state of these water resources. Land use and land cover have also undergone significant changes due to the need to provide resources to a growing population. Yet, the impact of the land-use and land cover change (LULCC) in addition to CC on the water resources of Africa is underexplored. Here we investigate how precipitation, evapotranspiration (ET) and river flow respond to both CC and LULCC scenarios across the entire African continent. We set up a Soil and Water Assessment Tool (SWAT+) model for Africa and calibrated it using the hydrological mass balance calibration (HMBC) methodology detailed in Chawanda et al. (2020a). The model was subsequently driven by an ensemble of bias-adjusted global climate models to simulate the hydrological cycle under a range of CC and LULCC scenarios. The results indicate that the Zambezi and the Congo River basins are likely to experience reduced river flows under CC with an up to 7 % decrease, while the Limpopo River will likely have higher river flows. The Niger River basin is likely to experience the largest decrease in river flows in all of Africa due to CC. The Congo River basin has the largest difference in river flows between scenarios with (over 18 % increase) and without LULCC (over 20 % decrease). The projected changes have implications for the agriculture and energy sectors and hence the livelihood of people on the continent. Our results highlight the need to adopt policies to halt global greenhouse gas emissions and to combat the current trend of deforestation to avoid the high combined impact of CC and LULCC on water resources in Africa.

Evaluating the joint effects of climate and land use change on runoff and pollutant loading in a rapidly developing watershed

Land use change ranks as the second most significant human-made factor affecting climate, following greenhouse gas emissions. Patna is rapidly expanding cities in Bihar state. Urbanization caused substantial alterations in land use patterns in Patna, driven by its rapid urban growth and increasing population. Urbanization and population growth caused a rapid increase in built structures to cater the demand, which caused reduction in vegetation, water body, and wasteland cover, due to which land cover changed. Land cover change detection plays a vital role in identifying its impact on diurnal temperature range (DTR). To study the impact, land use/ land cover change map for the city is produced from Landsat images for the study area Patna during 1995 to 2023. The supervised classification method is used to identify substantial changes in vegetation cover during 1995 and 2023 as a result of changes in land use and land cover. Landsat image supervised classification shows a growth of 47.80 percent in built-up areas in the last 28 years in the city of Patna. The classified image also shows a consistent decline of 31.74 percent in vegetation cover over the period of 28 years. Urbanization-driven changes in land use and land cover have led to a significant decrease of 20.24 percent in the near-surface DTR, average decrease of 12.54 percent in maximum temperature and an increase of 75.68 percent in minimum temperature of the city. The study offers scientific insights into how urbanization and human activities are impacting the eco-environment of the city.

Future changes in water resources, floods and droughts under the joint impact of climate and land-use changes in the Chao Phraya basin, Thailand

The Californian Floristic Province, ranging from Northern California, USA, to the northwestern portion of the state of Baja California, Mexico, is a region of great biological richness that has a high risk of loss of species due to the effect of human activities. The main stressor that threatens its biodiversity is the change in land use and vegetation cover, which severely impacts the environmental and socio-economic systems’ functioning, affecting the provision of environmental services including the maintenance of biodiversity. The Tijuana River Watershed (TRW) is located within this floristic province. It has experienced rapid population growth during the last 50 years, demanding development of infrastructure in areas where native vegetation existed. As a binational watershed, it is an ideal area to study the processes involved in fragmentation and connectivity of natural environments, since both countries, while sharing the same environment, contrast greatly in their economic and social systems, which impose different pressures to these shared natural resources. Our research addresses change in vegetation cover and land use in the TRW, analyzing the changes and differences between Mexico and the United States. This analysis will be a basis to propose future management strategies for the conservation of ecological processes and biodiversity, according to the policies and actions for land management and conservation in both countries.

The impact of land use- and climate change on the managed eco-geomorphic balance in the Alps

Shallow landslide susceptibility assessment under future climate and land cover changes: A case study from southwest China

The study aimed to assess the changes that have occurred in land use and land cover within the Maasai Mara landscape using remote sensed data from 1997 to 2017; examine the elephant distribution in relation to land use and land cover changes within the Mara landscape and to determine changes in elephant home ranges in relation to Land use and cover changes in the Mara landscape. In examining the land use and land cover changes on the elephant ranges and distribution, an integrated methodological approach was employed in which the changes that have taken place within the study area over a period of 20 years was determined by analysis involving a 10-year changes in land use and land cover using three epochs from 1997, 2007 and 2017 to generate six land use classes. The Maasai Mara Landscape (MML) supports one of the richest wildlife populations remaining on earth but over the last century, has experienced transformation notably through conversion of former rangelands into croplands. Elephants have both temporal and spatial requirements, which if not provided, render them vulnerable to the land-use practices. The study assessed land use and vegetation cover changes that have occurred and their effects on the elephant movements and distribution within the MML using an integrated methodological approach. The analysis revealed changes in land use and land cover classes over a period of 20 years for the three epochs, from 1997, 2007 and 2017. Elephant’s distribution has been restricted to areas of high vegetation densities within specific habitats hence accelerating the rate of habitat destruction and degradation due to their high densities. These changes have drastically reduced forage for elephants necessitating them to travel longer distances out of their home range in search for food. Human beings have caused land use and cover changes which have detrimental impacts on the ecosystem and ecosystem services. The Maasai Mara landscape supports one of the richest wildlife populations remaining on earth but over the last century, it has experienced land transformation notably through conversion of former rangelands used mainly for tourism and production of grains such as wheat. Land outside the national parks and the reserve is important to the future of elephant existence in Kenya. Little is known about how human occupation on these landscapes negatively affects elephants (Loxodonta africana) habitats, movement and ranges. This has been confirmed by the current continuous demarcation/fencing of land in most areas in Narok County. Elephants like other landscape species, have both temporal and spatial requirements, which if not provided, will render them vulnerable to the land use practices of people. The study aimed to assess the changes that have occurred in land use and land cover within the Maasai Mara landscape using remote sensed data from 1997 to 2017; examine the elephant distribution in relation to land use and land cover changes within the Mara landscape and to determine changes in elephant home ranges in relation to Land use and cover changes in the Mara landscape. The paper describes the different changes that have taken place within the MML and how these changes have affected elephant populations, their trend and distribution within the MML. In examining the land use and land cover changes on the elephant ranges and distribution, an integrated methodological approach was employed in which the changes that have taken place within the study area over a period of 20 years was determined by analysis involving a 10-year changes in land use and land cover using three epochs from 1997, 2007 and 2017 to generate six land use classes. The study found out that there were significant changes of various classes across the years. Forest, water and open shrubs coverages decreased from 1997 to 2017. Classification noted a serious problem within the study area of continuous increase of bare ground coverage across the study years. Elephant populations have been increasing within the area .at an annual rate of 2.69%. The animals are distributed all over the landscape. Distribution of elephants has been restricted to high densities within a specific habitat hence accelerating rate of habitat destruction and degradation due to their high densities within a specific habitat. These changes have reduced drastically foliage for elephants thus necessitating them to travel longer distances in search and as a result increases elephant home ranges.

We assessed the effects of historical (1931–1998) changes in both land use and climate on the water budget of a rapidly urbanizing watershed, Ipswich River basin (IRB), in northeastern Massachusetts. Water diversions and extremely low flow during summer are major issues in the IRB. Our study centers on a detailed analysis of diversions and a combined empirical/modeling treatment of evapotranspiration (ET) response to changes in climate and land use. A detailed accounting of diversions showed that net diversions increased due to increases in water withdrawals (primarily groundwater pumping) and export of sewage. Net diversions constitute a major component of runoff (20% of streamflow). Using a combination of empirical analysis and physically based modeling, we related an increase in precipitation (2.7 mm/yr) and changes in other climate variables to an increase in ET (1.7 mm/yr). Simulations with a physically based water‐balance model showed that the increase in ET could be attributed entirely to a change in climate, while the effect of land use change was negligible. The land use change effect was different from ET and runoff trends commonly associated with urbanization. We generalized these and other findings to predict future streamflow using climate change scenarios. Our study could serve as a framework for studying suburban watersheds, being the first study of a suburban watershed that addresses long‐term effects of changes in both land use and climate, and accounts for diversions and other unique aspects of suburban hydrology.

Earth’s soils and the global carbon (C) cycle have been profoundly affected by agriculture. Agricultural land-use and land-cover change (LULCC) date back to the early Holocene ~12,000 years ago when hunter-gatherers in the Fertile Crescent region of the eastern Mediterranean began using agricultural practices to manage soils. Since then, agriculture has spread across the globe and is now the dominant global land use with about 40% of the ice-free land area covered by croplands and grasslands. Especially, clearing of natural vegetation to make room for cultivating crops has released up to one-third of the soil organic carbon (SOC) stock from the top meter of soil. However, effects on the soil inorganic carbon (SIC) stock continue to be overlooked. Further, methane (CH4) is produced in anaerobic environments under agricultural practices, such as the sediments of wetlands, peatlands, and rice (Oryza sativa L.) paddies as well as by livestock production. Globally, up to 357 Pg (1 Pg = 1 Gt = 1015g) C pre-1850 and 168 Pg C post-1850 may have been released by agricultural land-use changes. To 2 m depth, about 133 Pg SOC may have been lost since the early Holocene. LULCC emissions from 1850 to 2015 have been estimated at 98.4 and 16.3 Pg C for crop and pasture land uses, respectively. This net C release together with emissions of CH4 and nitrous oxide (N2O) has contributed to increasing atmospheric greenhouse gas (GHG) concentrations and accelerating climate change. Climate change interferes with agriculture with severe negative effects. Thus, climate change adaptation and mitigation are necessary to sustainably intensify production amidst the increasing challenge of satisfying the demands for food, feed, fiber, and fuel of a growing, more affluent, and more animal products consuming population. Food-related GHG emissions are lower for plant-based diets. Improved soil management in agroecosystems can substantially reduce GHG emissions and sequester some of the atmospheric carbon dioxide (CO2) as SOC and oxidize some of its CH4. Additional benefits of agroecosystems with increased SOC stocks are more healthy and resilient soils. The hidden treasure of SOC has finally been recognized by policymakers. For example, to help address food security and climate change issues, the 4 per Thousand Initiative (4p1000) was proposed in December 2015 at COP21 in Paris to enhance the soil C stock on a large portion of the world’s managed soils by an average annual increase of 0.4% in 0–40 cm depth.