Modelling the Hydro‐Sedimentary Dynamics of a Mediterranean Semiarid Ungauged Watershed Beyond the Instrumental Period

Abstract

The development of reliable tools to quantify long‐term sediment budgets is critical to establish adequate environmental and management policies in semiarid Mediterranean regions. In this study, we apply a multidisciplinary methodology to estimate water and sediment yields in ungauged Mediterranean watersheds over a period of scarce instrumental data (i.e. second half of 19th and first half of 20th centuries). Runoff and precipitation reconstructions have been obtained using an integrative approach involving synoptic reanalysis models, regional climatic datasets, historical archives and palaeoflood proxies from natural archives. The resulting hydrological reconstruction has been implemented on a hydro‐sedimentary distributed model (i.e. TETIS) to understand the hydro‐sedimentary dynamics in the studied watershed. We highlight that, in our study area, regional‐data (instrumental, historical and sedimentary) based models show higher accuracy in the sediment yield and runoff reconstruction than synoptic reanalysis climate models. The modelled sedimentary dynamics for the studied period respond to a complex interplay between human activities and climate variability. During the 19th century deforestation and grazing activities combined with higher frequency on extreme runoff events resulted in higher runoff and sediment yield in the period 1863–1900. Over the 20th century, reduced precipitation and land abandonment led to a decrease in erosion rates and sediment yield although increased in 1945–1960 coinciding with a period of higher frequency of heavy rainfalls. This hydrological response to climate and human activities in the study watershed improves our understanding of plausible future trends of environmental degradation in small Mediterranean watersheds under different land use and climate change scenarios. This article includes supporting information which features an explanation of GILMCLIM downscaling model, The precipitation series resulting from the reanalysis data (Figure S1), an analysis of the different precipitation series used (Table S1) and an extensive explanation of how the relation between Puentes and Valdeinfierno reservoirs was considered. Copyright © 2016 John Wiley & Sons, Ltd.

Grazing activities in the southern central Pyrenees during the last millennium as deduced from the non-pollen palynomorphs (NPP) record of Lake Montcortès

“…5). This pattern has also been documented in other Mediterranean catchments where the coupled effect of deforestation and grazing with higher frequency of extreme run-off events resulted in higher sediment yield during the late 19 th century (Rodriguez-Lloveras et al 2017).…”

Facies variability and depositional settings of Laguna Salada de Chiprana, an Iberian hypersaline lake

“…Phase 1-2 (Units 6 and 5): ca 1700 to ca 1800 AD The basal units of the sedimentary sequence of Lake Chiprana broadly reflect the long-term effects of an increase in lake level that occurred during the 18th century. Palaeoclimatic reconstructions from saline lakes in the region (Morell ón et al, 2008;Corella et al, 2013) indicate an increase in the total annual precipitation within the Ebro Basin during this time, and other palaeoclimatic records also suggest increases in heavy rainfall events and flooding episodes throughout Northeast Spain during the mid-17th and 18th to mid-19th centuries (Llasat et al, 2005;Barriendos & Rodrigo, 2006;Corella et al, 2014Corella et al, , 2016Corella et al, , 2019Rodriguez-Lloveras et al, 2017). Despite this historical data, a recent hydrochemical modelling study by J ódar et al (2020) and agricultural activity associated with the nearby Civan Canal (Valero-Garcés et al, 2000b) throughout the last three centuries indicate that increasing lake levels during this time are more likely to be related to changes in anthropogenic activity within the region.…”

“…The basal units of the sedimentary sequence of Lake Chiprana broadly reflect the long‐term effects of an increase in lake level that occurred during the 18th century. Palaeoclimatic reconstructions from saline lakes in the region (Morellón et al ., 2008; Corella et al ., 2013) indicate an increase in the total annual precipitation within the Ebro Basin during this time, and other palaeoclimatic records also suggest increases in heavy rainfall events and flooding episodes throughout Northeast Spain during the mid‐17th and 18th to mid‐19th centuries (Llasat et al ., 2005; Barriendos & Rodrigo, 2006; Corella et al ., 2014, 2016, 2019; Rodriguez‐Lloveras et al ., 2017). Despite this historical data, a recent hydrochemical modelling study by Jódar et al .…”

Extreme Floods in Small Mediterranean Catchments: Long-Term Response to Climate Variability and Change

“…This palaeoflood archive provides physical evidence on the natural persistence of flooding, range of magnitude, and response to atmospheric circulation [14,15]. The understanding of hydrological response to environmental history contributes to the assessment of changes in the flood patterns linked to anthropogenic global change [3,16,17].…”