Lost Landscape: A Combination of LiDAR and APSFR Data to Locate and Contextualize Archaeological Sites in River Environments

Over the last few decades, river landscapes have been significantly transformed as a result of increased human impact. This transformation is evident in areas such as the middle Guadiana basin, where the impact of both agricultural and hydraulic infrastructures has led to the decontextualization of archaeological sites, resulting in a disconnection between archaeological sites and their own physical environment. In order to analyse the location and geographic contexts of sites from the first Iron Age in the middle Guadiana basin and to detect the existence of human settlement patterns, we designed a methodological approach that combines LiDAR and APSFR data (areas with potential significant flood risk). The main purpose of this method is to detect flood areas and assess the relationship between them and archaeological sites. The result allowed us to obtain a clearer understanding of these societies, their knowledge of the physical environment, and the causes and reasons behind their occupation of certain sites. The validation of the results demonstrated the versatility of this methodological approach, which can be extrapolated to analysing other regions and historical periods.

A Novel Approach to Harmonize Vulnerability Assessment in Carbonate and Detrital Aquifers at Basin Scale

The DRASTIC (D: Depth to water; R: Net recharge; A: Aquifer media; S: Soil media; T: Topography; I: Impact of vadose zone; C: Hydraulic conductivity) index is usually applied to assess intrinsic vulnerability in detrital and carbonate aquifers, although it does not take into account the particularities of karst systems as the COP (C: Concentration of flow; O: Overlying layers above water table; P: precipitation) method does. In this paper we aim to find a reasonable correspondence between the vulnerability maps obtained using these two methods. We adapt the DRASTIC index in order to obtain reliable assessments in carbonate aquifers while maintaining its original conceptual formulation. This approach is analogous to the hypothesis of “equivalent porous medium”, which applies to karstic aquifers the numerical solution developed for detrital aquifers. We applied our novel method to the Upper Guadiana Basin, which contains both carbonate and detrital aquifers. Validation analysis demonstrated a higher confidence in the vulnerability assessment provided by the COP method in the carbonate aquifers. The proposed method solves an optimization problem to minimize the differences between the assessments provided by the modified DRASTIC and COP methods. Decision trees and spatial statistics analyses were combined to identify the ranges and weights of DRASTIC parameters to produce an optimal solution that matches the COP vulnerability classification for carbonate aquifers in 75% of the area, while maintaining a reliable assessment of the detrital aquifers in the Basin.

Climate change and accommodation of water availability in transboundary rivers: lessons learned from the Guadiana basin

Historically, states have found it useful to regulate their relationship over their shared water resources via treaties. While treaties provide some element of predictability and certainty with regard to the future supplies of water to the riparian states, they also need to incorporate mechanisms that allow flexibility to respond to changes in the quantity of water available for allocation amongst the parties. This requirement is especially relevant when global climate change is causing freshwater resources to shrink. The legal regime of the Guadiana, as an example of a modern legal regime of a transboundary river, includes some provisions that permit the riparian states to accommodate the variability of the Guadiana's streamflow in response to climate change within the water allocation arrangements. The lessons learned from these provisions, which include periodical update of the historical mean precipitation values, updating the flow regime of the rivers and cancelling minimum flow requirements under special circumstances, may contribute to climate-proofing international transboundary agreements within the catchments where climate-change induced water scarcity poses a major threat.