The low-lying coastal basins of Ravenna (Italy) are at or below mean sea level and currently undergoing land subsidence, which exposes the basins to frequent inundation and groundwater and soil salinization. The surface water drainage becomes necessary to lower the water table head and further prevent flooding and waterlogging. The study examines the evolution of drainage apropos to climate change and land subsidence in the three main Ravenna coastal basins. Our findings show that the evolution of drainage is influenced by land subsidence, climate change variability, droughts, vertical seepage, and local water management. Land subsidence causes an increase in upward-directed vertical seepage of saline water through the shallow unconfined aquifer into the drainage channels of the coastal basins, thus leading to an increase in drainage through time. At a seasonal timescale, the rate of pumping depends on antecedent rainfall and soil–water storage. The warming extremes indices, specifically drought indices, show to be more significant than rainfall indices trends to monitor drainage evolution. Drought indices permit easy comparison of dryness or wetness severity with drainage evolution along their time scale. The co-occurring anthropogenic and natural factors involving in the increasing drainage rate will affect decadal and seasonal water management policies in the area. The implications of increasing drainage rates, long periods of drought with limited rainfall, and increasing temperature will further worsen freshwater availability in this coastal area already experiencing soil and water salinization. However, drainage of this low-lying territory has effectively mitigated rising water tables and avoided flooding. Our study has shown that each coastal basin behaves differently in terms of sensitivity to land subsidence and climate extremes. Therefore, when using drainage data time series for water management purposes, one should account for past management practices and for the specific sensitivity of each basin to external factors.

Abstract. Lake Chad is a transboundary freshwater body located in the extreme south of the Sahara Desert. Many centuries ago, the synergies between nature and human activities in the basin were in harmony; and nowadays, the manifestation of unsustainable human activities and drier climate in the basin is now evident. This study assesses the water insecurity and associated environmental issues in the area using the combined Driver-Pressure-State-Impact-Response (DPSIR) and System-Approach-Framework (SAF) frameworks. In achieving this, we conducted literature review to establish the major effects and possible consequences of water scarcity in the area. The SAF defines the Lake boundaries and eventually links the active stakeholders involved. On the other hand, the DPSIR reveals that about 90 % of inhabitants depends on agriculture, with warming (temperature) significantly increasing in the basin (0.22 ∘C per decade) – socio-economic and natural Drivers respectively – as well as increase in population. Pressures include input from irrigation systems, river–flow modification, limited rainfall, and prolonged drought periods. These pressures have led to change in the state of Lake Chad, like freshwater shortages and loss of ecological status. Impacts on human welfares includes mass displacement, unemployment, paralyzed socio-economic activities, and social unrest. The societal-Response has prompted various measures like the launch of campaigns and awareness, planned Inter-Basin-Water-Transfer (IBTW), and several policy changes for better governance. Conclusively, the restoration of Lake Chad solely depends on climate conditions and management policies. However, this study recommends the prioritization of monitoring systems, water-allocation plans, ecological plans, and modelling tools for better decision processes.