HS5.6

Many regions in the world face declining water availability and increasing water-related risks, as a result of pressures such as environmental degradation, global warming, and population growth. Sustainable and integrated land management is an important tools to improve and safeguard catchment water resources, and to minimize flood and drought risk. However, land management to optimise water security is still severely hindered by a lack of hydrological information about the impact of different management practices on the catchment hydrological response. Statutory hydrological monitoring networks tend to be sparse in most of the world, and focused on operational purposes such as water supply and flood risk. Here we present the case of iMHEA, a participatory hydrological monitoring network in the tropical Andes that aims at characterising the hydrological impact of different land management practices in the upper Andes, especially conservation, livestock grazing, and forestry. The network monitors currently 59 catchments in 22 Andean sites from Venezuela to Chile. It operates as a community of practice, exchanging experimental designs, technical expertise on monitoring equipment, protocols, and experience. It largely follows a pairwise catchment comparison approach, which has been able to show statistically significant trends in land-use impacts on flow characteristics such as runoff ratio, baseflow index, and slope of the flow duration curve. Thanks to rigorous technical support, the generated data are generally of high scientific quality and reliability. The involvement of stakeholders with a policy background, such as NGOs and government agencies, is key to dissemination and operational uptake of the scientific results. As such, iMHEA can be considered a success story, which has created a step change in scientific evidence for land use planning in the Andes. However, several challenges remain. One is the experimental design, which is not yet able to accommodate all the specific interests and challenges that iMHEA members are faced with. Longevity and long-term financial sustainability also remains a major challenge. Lastly, improvements are needed to process and dissimenate the results to specific stakeholders, and especially local communities and governments.

How to cite: Buytaert, W., Acosta, L., Drenkhan, F., Perez, K., Antiporta, J., and Ochoa Tocachi, B.: Assessing land use impacts on catchment hydrology with participatory monitoring: lessons for experimental design, network building, and policy support, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10578, https://doi.org/10.5194/egusphere-egu22-10578, 2022.

Due to urbanization, land use and cover change (LUCC) are considered one of the concerns in groundwater recharge by precipitation because urban development increases impermeable surfaces. The main objective of this study is to investigate the effects of LUCC on groundwater recharge by precipitation in South Korea. Ten monitoring wells were selected based on a significant difference in LUCC using Arc-GIS software. Then lag-time between precipitation and groundwater level response was estimated based on correlation coefficients computed from cross-correlation function (CCF) and moving average (MA) for 3 years before and after LUCC. As a result of the estimated lag-time, monitoring wells were classified into two groups: group Ⅰ (n = 3) with more than 30% increase in the impermeable surface and group Ⅱ (n = 7) with less than 30% increase in the impermeable surface. Group I showed a significant increase in lag-time computed from MA (28 to 127 days) and CCF (6 to 19 days), while group II showed no significant difference in lag-time. The results of this study indicate that groundwater recharge is regulated by the occurrence of the impermeable surface, interrupting direct groundwater recharge from rainwater infiltration.

How to cite: Heo, J., Jeong, S., Jang, S., Kim, L., Kwon, D., and Yang, M.: Impact of land-use/cover changes due to urbanization on groundwater recharge by precipitation in South Korea, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1584, https://doi.org/10.5194/egusphere-egu22-1584, 2022.

In eastern Germany, the Czech Republic, and Slovakia, historic policies have led to large, monocropped agricultural landscapes resulting in degradation of traditional landscapes with impacts on the local water and climate cycles. In the last 20 years, the expansion of urban and industrial areas has added to this landscape degradation. The growing interest in nature-based solutions, including landscape-based water-retention measures, is a response to reversing landscape degradation, rejuvenating ecosystem services, and mitigating the impacts of large-scale commercial agriculture and climate change. In this study, the costs and benefits of water-retention measures in east Germany, the Czech Republic, and Slovakia are assessed. Results indicate that water-retention measures, should they be implemented throughout the study area, offer potentially increased water availability over all land use classes assessed, help to increase local crop productivity, and aid in local landscape cooling. Croplands are suggested as being the best value for money, offering the greatest volume potentials (mean = 88 million m³), cooling effects (mean = -1.6°C), and productivity gains (mean = €66 million yr^-1), while also being the cheapest to implement per unit area. Differing policies in the three states will likely result in non-uniform selection or implementation of measures. Future research should focus on local-level studies offering greater practical messages beyond the regional-level analysis conducted in this work, as well as ways towards harmonising policy across the states. This work contributes to the growing body of literature assessing the costs and benefits of water-retention measures, including the potential for landscape cooling, lowering temperature gradients, and ecosystem restoration. As the world urbanises, and as more land is converted to homogeneous cropland, such measures may prove critical in mitigating climate change, landscape drying, flood runoff, and soil and nutrient loss.

How to cite: Susnik, J., Masia, S., Kravčík, M., Pokorný, J., and Hesslerová, P.: Estimating the costs and benefits of landscape-based water retention measures as nature-based solutions to mitigating climate impacts in eastern Germany, the Czech Republic, and Slovakia, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1636, https://doi.org/10.5194/egusphere-egu22-1636, 2022.

Future sectoral-specific water withdrawals at a temporal resolution capable of representing patterns in seasonality and a commonly used spatial resolution are an important factor to consider for energy, water, land and environmental research.  Projected water withdrawals that are harmonized with assumptions for alternate futures that capture socioeconomic and climatic variation are critical for many modeling studies on future global and regional dynamics. Here we generate a novel global gridded water withdrawals dataset by coupling Global Change Analysis Model (GCAM) with a land use spatial downscaling model (Demeter), a global hydrologic framework (Xanthos) and a water withdrawal downscaling model (Tethys) for the five Shared Socioeconomic Pathways (SSPs) and four Representative Concentration Pathways (RCPs) scenarios. The dataset provides sectoral monthly data at 0.5° resolution for years 2015 to 2100. The presented dataset will be useful for both global and regional analysis looking at the impacts of socioeconomic, climate and technological futures as well as in characterizing the uncertainties associated with these impacts.

How to cite: Khan, Z., Thompson, I., Vernon, C., Graham, N., Wild, T., and Chen, M.: A global gridded monthly water withdrawal dataset for multiple sectors from 2015 to 2100 at 0.5° resolution under a range of socioeconomic and climate scenarios, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6476, https://doi.org/10.5194/egusphere-egu22-6476, 2022.

River deltas represent globally important population centres and areas for food production, embedded on a nexus of land-water production. Yet pressures at the sea-land interface in these coastal areas are increasing from population growth, economic expansion and climate change. Over time, delta human populations have shifted from sea to land-based food production, the former more associated with local communities’ subsistence and the latter with exports of food products elsewhere leading to potentially irreversible land use-land cover changes (LULCC). While livelihood diversification by switching between or including both sea and land food production systems, could promote resilience and increase food security, food production based on sea and land-based resources has seldom been addressed in tandem, and potential unintended spill-over effects and LULCC may emerge which may jeopardise both. Here we examine the extent to which deltas have food production systems based on sea and land-based food sources (biomass, calories and protein) and which factors could drive these relationships, as transitions between sea and land food production in deltas may have local and global food security implications.

We use global datasets across 235 large deltas, which include information on food biomass, calories and proteins from sea (fishing and aquaculture) and land (crops and livestock) production systems. Based on these indicators of food production, we calculated a sea:land ratio to examine to what extent food production of each delta is weighted towards the sea or land. We find clear geographical patterns in the sea:land food production ratio in global deltas: the majority of the deltas exhibit a dominance of sea-based food production (particularly those at higher latitudes) while the deltas in most of Europe, Central and Southern America, show a dominance of land-based food production. We found similar geographical patterns for biomass, calories and protein, with the relationship being stronger for protein than biomass or calories. We then examined how the sea:land ratio changes along gradients of human population density, and condition of the local ecosystems. Surprisingly, we found no relationship between population density and the sea:land ratio, indicating other factors may be at play (e.g., local context). Indeed, we found that as food production is mostly due to land contributions (i.e., the lower the sea:land ratio) the stronger the negative relationships with ecosystem conditions such as biodiversity intactness, soil and water quality. These results suggest that transitions between sea and land food production and subsequent LULCC can therefore be both complex and problematic in deltas globally, as these may represent switches in not just biomass but also nutritional quality, and may have severe implications for local ecosystem health and functioning. Increasing our understanding of what drives these transitions and associated LULCC at the nexus between land-water, and their effects, will allow more sustainable management of coupled food production systems and associated earth system processes.

How to cite: Santos, M. J., Reader, M. O., and Oostdijk, M.: Sea-land transitions in food supply across global deltas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7398, https://doi.org/10.5194/egusphere-egu22-7398, 2022.

The agricultural sector of Senegal is prone to drought and climate change impacts. Despite this, the country counts less than 5% of irrigated lands, suggesting that its national agriculture is still strictly dependent on the rainy season. Moreover, rainfall is characterized by the presence of great variability, both on interannual and interdecadal timescales. In this framework, a research gap is represented by the lack of analyses on how much the current agricultural practices can be resilient, and on what water management strategies can be effective against climate change.

Using FAO’s AquaCrop crop-growth model, made up of a set of four sub-model components (climate, crop, soil, and management) to simulate a crop cycle, we simulated plausible climate change scenarios at different fertility levels, testing the efficiency of tied ridges water harvesting for the maize crop in the Fatick region, Senegal. Non-conservative parameters were adjusted with crop data collected within the project "Rain, Forest and People" of the International Rainwater Harvesting Alliance (IRHA, https://www.irha-h2o.org/en/projects/la-pluie-la-foret-et-les-hommes) while calibration and validation were performed with regional yield data.

Considering the current climatic scenario and soil fertility, tied ridges did not significantly impact the maize yields. Rainfall amount was enough for maize production and to avoid high water stresses along the cropping season. Under climate change scenarios, high reductions in yield were registered up to 70% in optimally fertilized soil and 50% in conditions of fertility stress.  Tied ridges only slightly increased yields up to 3.8% when a high reduction of rainfall occurred. When also considering the occurrence of dry spells in addition to climate change, maximum yield reductions do not exceed the values found without dry spells. However, in such context, tied ridges water harvesting performed better against climate change, especially under full fertilization management.

Our results highlighted how the current maize production in the Fatick region of Senegal is sustainable in the current climate scenario, while it could be potentially impacted by climate change in the near future. In a pessimistic climate change scenario with dry spells occurring in the rainy season, in-situ water harvesting has the potentiality to avoid excessive crop losses.

How to cite: Castelli, G., Setti, A., Villani, L., Ferrise, R., and Bresci, E.: Modelling the impacts of water harvesting and climate change on rainfed maize yields in Senegal, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9675, https://doi.org/10.5194/egusphere-egu22-9675, 2022.

The application of Water-related Ecosystem Services (WES) concept in water resources planning can support the development of productive activities and, at the same time, sustain local ecosystems. Gaining insights into the ecohydrological behavior of a basin and the anthropogenic pressures on the available water resources requires the spatial explicit evaluation of WES for the identification of the strategies to explore the sustainable coupling of biosphere and anthroposphere. By integrating hydrological modelling and Water Footprint (WF) analysis, this study aims at evaluating a Water Ecosystem Services Footprint (WESF) associated with the agricultural sector analyzing both the supply and demand of WES.

Combining the evaluation of WES demand, determined by the agricultural sector using the WF assessment methodology and the quantification of WES supply by applying the Soil Water Assessment Tool (SWAT), the proposed methodology introduces green, blue, and gray WESF indicators to identify the main hotspots connected to the agricultural production. The methodology is applied to a specific case study in the upstream part of the Arno River basin (Central Italy).

WESF represents an operative tool to look at agricultural water management from an ecosystem-based perspective, introducing a useful approach that potentially can be extended to different sectors. The results allow the evaluation of WESF spatial pattern, identifying the most critical areas in the catchment and supporting a stronger integration of water management with ecosystems conservation.

How to cite: Pacetti, T., Castelli, G., Schroeder, B., Bresci, E., and Caporali, E.: Evaluating the Water Ecosystem Services Footprint to support agricultural water management in Central Italy: a watershed scale approach, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12434, https://doi.org/10.5194/egusphere-egu22-12434, 2022.

The Maroni River in the Guiana Shield marks the border between  French Guiana and Suriname. In the Maroni River Basin, as in many transboundary river basins of the world, socio-political borders criss-cross through natural ecosystems and hence intersect through ecological boundaries. As neighbouring countries share ecosystems, they also share inherent ecosystem processes, functions and, hence, the ecosystem services (ES) that these areas provide. However, life and land uses are changing in the river basin. A growing need for land, urbanization, a decrease of shifting cultivation patterns towards smallholder agriculture and a run for gold put pressure on natural ecosystems.

Our work on ES in this area was twofold: under the umbrella of the ECOSEO Project, we conducted a first ecosystem services assessment for the river basin, extracted from two national ES assessments on the base of Land Use Land Cover data. In participatory expert workshops in Paramaribo, Suriname and Cayenne, French Guiana, stakeholders from the territory assessed the capacity of abundant ecosystem types to supply 21 different ecosystem services using a matrix-based approach. A comparative assessment of workshop results showed that experts in both territories shared a similar understanding on ES supply capacities despite the different cultural and socio-political contexts of both territories. Whilst Suriname’s economy still depends on the primary sector and exploitation of natural resources, French Guiana as Outermost Region of the European Union has to adhere to the much stricter EU/French environmental legislation. Between 2015 to 2020, , land uses in Suriname changed much stronger then in French Guiana. Gold mining is the major driver for deforestation, especially on the Surinamese side of the river basin, followed by agricultural expansion. An overview of the ecosystem service bundles presents a snapshot of ecosystem service supply, and allows to quantify changes in ES supply.

The expert-based matrix assessment showed direct changes in ES based on LULC changes, a qualitative assessment was added. We conducted 14 in depth interviews with local and indigenous population in the Upper Basin in 2019. Hereby, land use changes and their effects on ES supply were thematized. Illegal gold mining activities and intensification of agriculture were mentioned to contribute strongly to the degradation of ecosystems. Especially regulating ES in the Upper Maroni River were affected, with consequences on freshwater quality, supply of wild foods and fish and transportation for the entire lower River Basin.

As LULC changes, especially gold mining-related activities, on both sides of the river have a severe degrading effect on ecosystem condition and related ES supply, cross- or transboundary conservation efforts are needed to safeguard ecosystems and their services for the population on both sides of the Maroni River.

How to cite: Sieber, I. M., Campagne, S., and Burkhard, B.: Land Use Changes and Ecosystem Services Supply in Transboundary River Basins. The Case of the Maroni River (French Guiana/Suriname), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13353, https://doi.org/10.5194/egusphere-egu22-13353, 2022.

Science-informed models provided undoubtable indications of the crucial interlinkages that govern the Water, Energy, Food and Ecosystem (WEFE) dynamics. Managing natural and urban ecosystems without considering WEFE interlinkages may determine undesirable consequences in terms of safety and sustainability from multiple perspectives (e.g. environmental, social, economic). From short term operations to long term projections, science evidences depict the pivotal importance and multiple benefits of embracing WEFE Nexus approaches. Nevertheless, while science and technological advancements are pushing ahead such understanding, several technical and non-technical barriers still avoid the WEFE Nexus transition. WEFE-related Multi-Sector, Multi-Disciplinary and Multi-Actor cross-cooperation and mutual trust are still lacking in actual water and land management strategies. Moreover, stakeholders and citizens are not adequately informed and involved. WEFE Nexus policies are also generally missing.

The NEXUS Nature Ecosystem Society Solution or NEXUS-NESS project - funded by the PRIMA Programme under the 2020 Nexus Innovation Action - seeks to address this issue of paramount importance for the Mediterranean regions. NEXUS-NESS aims to co-produce and co-test with stakeholders WEFE Nexus management plans for fair and sustainable allocation of resources. At the same time a technological solution and tailored procedures are co-tested to provide actionable information and easy-to-follow guidelines for WEFE Nexus operators and stakeholders in selected case studies.

This contribution aims to specifically focus on the transdisciplinarity concept that was a guiding principle of the NEXUS-NESS project design and mission. The NEXUS-NESS solution transdisciplinary datasets and tools seek to interlink the WEF Nexus components with a three-fold conceptualization of the Ecosystem component (Environment, Economy, Engagement/Society). NEXUS-NESS will operationalize the adoption of a WEFE Nexus bottom-up approach in four different case studies employing Living Lab and Responsible Research And Innovation (RRI) principles. Results from the first year of project development are here illustrated with specific focus on the the Val di Cornia (Italy), Duero basin (Spain), Wadi Naghamish (Egypt) and Wadi Jir basin (Tunisia) Nexus Ecosystem Lab (NELs) initiation activities and feedbacks co-processed with local and regional stakeholders.

How to cite: Nardi, F. and the NEXUS-NESS Project team: Advancing transdisciplinary knowledge and procedures for mainstreaming WEFE Nexus: insights from the PRIMA NEXUS-NESS projects, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13291, https://doi.org/10.5194/egusphere-egu22-13291, 2022.