A Simplistic Approach for Assessing Hydroclimatic Vulnerability of Lakes and Reservoirs with Regulated Superficial Outflow

Kleoniki Demertzi,Dimitris Papadimos,Vassilis Aschonitis,Dimitris Papamichail

doi:10.3390/hydrology6030061

Kleoniki Demertzi, Dimitris Papadimos + Show 2 more

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https://doi.org/10.3390/hydrology6030061

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Abstract

This study proposes a simplistic model for assessing the hydroclimatic vulnerability of lakes/reservoirs (LRs) that preserve their steady-state conditions based on regulated superficial discharge (Qd) out of the LR drainage basin. The model is a modification of the Bracht-Flyr et al. method that was initially proposed for natural lakes in closed basins with no superficial discharge outside the basin (Qd = 0) and under water-limited environmental conditions {mean annual ratio of potential/reference evapotranspiration (ETo) versus rainfall (P) greater than 1}. In the proposed modified approach, an additional Qd function is included. The modified model is applied using as a case study the Oreastiada Lake, which is located inside the Kastoria basin in Greece. Six years of observed data of P, ETo, Qd, and lake topography were used to calibrate the modified model based on the current conditions. The calibrated model was also used to assess the future lake conditions based on the future climatic projections (mean conditions of 2061-2080) derived by 19 general circulation models (GCMs) for three cases of climate change (three cases of Representative Concentration Pathways: RCP2.6, RCP4.5 and RCP8.5). The modified method can be used as a diagnostic tool in water-limited environments for analyzing the superficial discharge changes of LRs under different climatic conditions and to support the design of new management strategies for mitigating the impact of climate change on (a) flooding conditions, (b) hydroelectric production, (c) irrigation/industrial/domestic use and (d) minimum ecological flows to downstream rivers.

Highlights

Lakes and reservoirs are important assets due to the high value of ecosystem services that they provide [1,2,3,4]
Hydrology 2019, 6, 61 model complexities can be selected, starting from extremely data demanding and complex models such as MIKE SHE [15,16], GSFLOW [17], WATLAC [18], SMS [19], QGIS-SWAT [20], or using simpler methods such as those provided by Bracht-Flyr et al [21], Yang et al [22] and others
The overall analysis and the provided results of the modified Bracht-Flyr et al (2013) methodology showed that it can provide (a) a simple evaluation of the mean annual AB /AL ratio of an LR with regulated superficial outflow and (b) a water balance of the AT area that hosts the LR, considering steady state conditions based on the mean climatic conditions of the current studied period and for the future climate projections of general circulation models (GCMs)

Summary

Introduction

Lakes and reservoirs are important assets due to the high value of ecosystem services that they provide [1,2,3,4]. If the worst predictions of general circulation models (GCMs) about climate change become true, lakes/reservoirs (LRs) will hardly manage to maintain their current conditions in terms of quantity and of quality [5,6,7,8,9]. Under such conditions, the local authorities will face great challenges for setting strict measures able to preserve and restore the conditions of LRs [10,11,12,13]. The method is applied for water-limited environments (mean annual potential evapotranspiration greater than precipitation) under steady-state conditions and takes into account the mean annual precipitation, mean annual potential evapotranspiration and an empirical factor that describes the effect of the ratio between the terrestrial area of the basin that drains to the lake AB versus the area of the lake

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