Sea level rise (SLR) produced by climate change affects severely coastal ecosystems which are currently being impacted by sea level rise in many parts of the world. In relation with coastal wetlands, the most relevant induced effect will occur on water and soil's salt content, especially in areas below sea level. This could lead into a reduction of habitat for the wetlands' biota. In this context, this research assesses the SLR related risk in the Júcar River Basin District (JRBD). Hazard, exposure, impact, vulnerability, and risk maps have been elaborated. The design and application of measures is prioritized in those areas classified as Very High risk with the aim of improving coastal ecosystems' climate change adaptation. In Western Mediterranean coast, average sea level (ASL) will rise 0.16 m (2026-2045) and 0.79 m (2081-2100) referred to the reference period (1986-2005). High-end scenarios indicate that ASL will rise 1.35 m-1.92 m (2081-2100). The risk analysis results show that 90% of JRBD area affected by SLR, corresponds to coastal wetlands. Half of the affected area belongs to L'Albufera de Valencia wetland with 32.44 km² below sea level, which represents a water volume of 42.64 hm³ (2026-2045) and a surface between 72.53 and 138.96 km² representing from 118.36 to 289.70 hm³ (2081-2100). In the case of L'Albufera de Valencia the impact will be throughout the 21st century, the average rate of SLR will leap from 4 to 11 cm per decade, therefore MSL will reach the current wetland levels by 2040-2045. This makes necessary to modify the lake's management rules, which will lead to an increase of 40 hm3 in water storage and a reduction in water's renewal time compared to current rates (from 15 to 5 times a year).

The Mediterranean is one of the most vulnerable regions to climate change impacts. Climate change scenarios predict that water temperature will increase up to 2.2–2.9ºC by the end of the century in Mediterranean rivers. This will cause an impact on water quality (oxygen dissolved reduction), reduce the available habitat of cold-water fish species and affect macroinvertebrates. Risk assessment methodology develops indicators that integrate hazard, exposure and vulnerability. Risk maps are key tools to prioritize the areas in which adaptation measures should be implemented in order to improve the adaptive capacity of ecosystems. The risk of habitat loss and ecosystem damage is very high in Mediterranean rivers. For RCP8.5, the 80% of the waterbodies that currently have brown trout presence are in High Risk (HR) or Very High Risk (VHR) of disappearing in the long term future (2070–2100) and the 35% in the short term (2010–2040). It will affect the middle sections first and the headwaters of the rivers later. The 92% of the waterbodies are in HR-VHR of macroinvertebrate family’s affection (2070–2100) and dissolved oxygen may be reduced by 0.5–0.75 mgO₂/l (2070–2100). The restoration of the riverside vegetation is the main adaptation measure. This reduces significantly the stream temperature. Other measures are the groundwater protection and cold-water discharge from the reservoirs.

Water scarcity will increase due to climate change, especially in basins that are currently highly stressed. The Mediterranean area is one of the most vulnerable areas in the world, with a predicted natural water resource reduction of 20% to 35% at the end of the century, due to temperature increases and a 10–20% precipitation reduction. Water scarcity indices, including gross abstraction, net abstraction, and consideration of environmental requirements, can be efficiently used to analyse the effects of climate change in water resource systems and determine the main measures to adapt these systems to climate change. Increasing the reclaimed water use, seawater desalination, irrigation efficiency, and interconnecting water resource systems are the main measures to adapt basins under water stress and reduce their vulnerability to climate change. In the Júcar River Basin District (JRBD), with a 20% reduction in natural water resources, the main measures are: increasing the reclaimed water use in agriculture from 20% to 50% (91 hm³/year to 230 hm³/year), increasing seawater desalination from 30 to 55 hm³/year, increasing irrigation efficiency from 54% to 80%, and finally, fully developing the current water interconnections between water resource systems. In highly stressed basins, moving water from downstream to upstream using energy supplied by photovoltaic systems can help adapt river basins to climate change.

Sea level rise produced by climate change severely affects coastal ecosystems. The increase in the area below sea level facilitates the penetration of the marine wedge and causes an increase in soil salinity. Coastal wetlands are areas of great ecological importance due to the richness of flora and fauna that inhabit them. A change in salinity conditions could lead to a reduction or loss of habitat for the wetland biota. Based on RCP4.5 and RCP8.5 CMIP5 multimodel scenarios, in the Western Mediterranean coast, the sea level will rise 0.16 m in the short term (2026 - 2045) and 0.79 m in 2100. Also, high-end scenarios indicate that sea level will rise between 1.35 m and 1.92 m in the long term.A sea level rise analysis has been developed in the coastal wetlands of Júcar River Basin District (JRBD). The results show that coastal wetlands are the mainly area affected in the JRBD, so the 90% of the area under the sea level are wetlands. L’Albufera de Valencia is the main wetland in this basin and, also the main wetland affected. It is an anthropized humid zone, regulated by users through gates to preserve the adequate water level for agricultural and environmental purposes such as rice cultivation around the lake and bird habitats conservation, especially in winter. The outcome of the study shows a significative increase in the area below the sea from 507 ha and 4.2 hm3 of water volume at present to 3,244 ha that represents 42.6 hm3 of water volume in the short term. In the long term, the area below the sea is 7,253 ha which means 118.4 hm3 of water volume in the percentile 50 scenario and, in the worst extreme scenario, it is 13,896 ha that represents 289.7 hm3 of water volume. This leads to a redefinition of the lake management levels as a climate change adaptation measure to prevent the lake salinization and severe impacts in the lake ecosystem. L’Albufera lake levels need to be increased in the next years to avoid the sea water penetration, related to the sea level rise. Thus, in the short term the lake levels must be increased around 0.16 m and, in the long term, L’Albufera levels must be increased around 0.8 m.