This research aims to assess the hydrogeochemical evolution of the groundwater in Oued souf valley for drinking and irrigation purposes. To achieve this, 49 groundwater samples from the complex terminal were examined and treated concurrently with multivariate statistical methods, geostatistical modeling and the WQI (water quality index). Focusing on the physico-chemical parameters, Q mode clustering analysis detected four major water groups, where the mineralization augmented from group 1 to group 4. The hydro-chemical type was the same, Ca-Mg-Cl-SO₄ for all the groups. Calcite, dolomite, anhydrite, and gypsum would be the dominant reactions with the undersaturation of evaporates minerals, based on geochemical modeling, while the carbonate minerals are precipitating. Geostatistical analysis using ordinary Kriging demonstrated the exponential semi-variogram model fitted for EC (electrical conductivity), Ca²⁺ (calcium), Mg²⁺ (magnesium), K⁺ (potassium), HCO₃⁻ (bicarbonate), Cl⁻ (chloride), and SO₄²⁻ (sulfate). At the same time, the rational quadratic model was the best-fitted semi-variogram model for Na⁺ (sodium) and NO₃⁻ (nitrate). EC, SO₄²⁻, and NO₃⁻ have a strong spatial structure, while Ca²⁺, Na⁺, K⁺, and HCO₃⁻ have a moderate spatial structure. Moreover, there was a weak spatial structure for Mg²⁺ and Cl⁻. The WQI shows that CT (complex terminal groundwater aquifers) are not suitable for drinking and their quality for irrigation fluctuates from excellent to moderate quality.

A hydrochemical characterization of the waters of the study region (North-East Algeria) was carried out following samples taken at 36 thermal springs and their effluents during May 2022. The analysis of the waters allowed to establish the chemical facies and their classification according to the Stuyfzand's method and to deduce the aptitude of these waters for irrigation and the risks of salinity. The results revealed physico-chemical characteristics, relatively, variable. Q-mode cluster analysis was applied to the thermal water, generated four (4) groups clusters. Group1 represent a group of waters with low salinity dominatedby Na-HCO3; Stuyfzand's classification indicated that the waters are fresh-brackish with moderate to moderately high alkalinity. Taking into account the classification of Richards; we were able to identify the presence of the C3S1 class for the majority of the stations. The C3S1 class designates waters that can be used without any particular control for the irrigation of crops that are moderately tolerant to salts. These waters have average EC values of 3616.3µS/cm allowing their use in a less restrictive way for irrigation. Potential environmental effluents from the thermal spas could pollute both irrigation and drinking water, which represents a danger to the health of the region's inhabitants.

Understanding the impact of climate change on waterbirds, particularly those of conservation concern, is essential for their long-term management and effective conservation. In arid regions such as North Africa, wetlands of international importance have been affected by severe drought events, but their impact on waterbirds is still not well understood. Here, we assess the population dynamics of four emblematic resident species (Aythya nyroca, Marmaronetta angustirostris, Oxyura leucocephala, and Porphyrio porphyrio porphyrio) in a North African Ramsar site (Garaet Hadj Tahar marsh, Northeast Algeria), and determine the climatic variables (temperature, precipitation, and drought index) that best predict the change in abundance in wintering and breeding seasons. We used a long-term survey of regular counts during the wintering and breeding seasons of 2002–2019. The temporal trend of waterbird abundance differed between species and seasons. Species showed different sensitivities to different climatic variables at different time windows preceding the wintering and breeding seasons. We found that the population dynamics of the endangered O. leucocephala in the wintering and breeding seasons were best predicted with the drought index, whereas those of P. p. porphyrio were best correlated with maximum temperature. Population dynamics during the wintering and breeding season of the two other species were best explained with either maximum temperature, precipitation, average temperature, or drought. Species responded differently to warming and drought. The most endangered species (O. leucocephala) showed population declines in drier years, whereas less threatened species (A. nyroca, M. angustirostris, and P. p. porphyrio) exhibited either positive or negative correlations. The observed temporal increase in vegetation cover was positively correlated with the wintering population size of O. leucocephala, as well as the breeding population size of P. p. porphyrio and M. angustirostris. These findings highlight the urgent need for climate-adaptive conservation strategies to sustain wetland biodiversity and ecosystem resilience in the face of increasing climate stressors, aligning with the global sustainability goals for biodiversity conservation and ecosystem management. Our results suggest that future increases in temperatures and drought severity might threaten endangered waterbirds and benefit more common species in the region.