Patterns of hydrological alteration in the Iberian Peninsula Francisco J. Peñas, Oscar Belmar & José Barquín DO RESERVOIRS WITH A SIMILAR OPERATION RULE PRODUCE ALWAYS THE SAME EFFECT? Patterns of hydrological alteration in the Iberian Peninsula Francisco J. Peñas, Belmar, O. &. & Barquín, J. Environmental Hydraulics Institute “IH Cantabria”, University of Cantabria.

Background: Project HYDRA HYDRA focuses on the study of how river ecosystems are affected by HYDROLOGICAL ALTERATION from dam operation and land use changes and will explore how these effects are translated to river service provisioning.

Background: Project HYDRA Account for different levels of biological organization Using a Virtual Watershed approach: Order, model and communicate environmental information Assess of the Hydrological Alteration new tools for Ecosystem Service Valuation such as ARIES

REGIONAL Hydrological alteration assessment Case by case studies Introduction The assessment of Hydrological alteration REGIONAL Hydrological alteration assessment Case by case studies POST-DAM PRE-DAM ♦ Not available data Hydrological classifications Peñas et al., 2016. Ecological indicators ♦ Natural hydrology of the river ♦ Use of the reservoir Hydrological Index A Before After % of change

Objectives The main objective of this work is to: Infer a general insight of the hydrological alteration in the northern half of the Iberian peninsula. Analyse the variability of the hydrological alteration according to the natural hydrology of the river and the size and main use of the reservoirs Hydrological classification Natural flow regimes Altered flow series Downstream reservoirs Analyse deviation from natural condition

Study area and initial data Study area and hydrological data Methods Study area and initial data Cantábrico Galicia Costa Miño-Sil Cataluña Duero Ebro ● Series of daily mean flow (Gauge stations) ● Criteria to select unmodified gauges Visual examination of hydrographs Elimination of years with gaps > 30 days Retention of gauges with records longer than 7 years for the period 1976-2006 Study area and hydrological data

Study area and initial data ENVIRONMENTAL INFORMATION Methods Study area and initial data FLUVIAL NETWORK Climate Geology Land Cover & Land Uses ENVIRONMENTAL INFORMATION

Study area and initial data HYDROLOGICAL INFORMATION Methods Study area and initial data HYDROLOGICAL INFORMATION 679 Gauge stations (mean daily flow)

Study area and initial data HYDROLOGICAL INFORMATION Methods Study area and initial data HYDROLOGICAL INFORMATION Hydrological classification 392 unmodified flow records 679 Gauge stations (mean daily flow) Hydrological alteration analysis 287 altered flow records

Study area and initial data HYDROLOGICAL INFORMATION Methods Study area and initial data HYDROLOGICAL INFORMATION 392 unmodified flow records 679 Gauge stations (mean daily flow) Visual examination of hydrographs Gaps < 30 days Records longer than 7 years Period 1976-2006 221 Gauge stations

Study area and initial data HYDROLOGICAL INFORMATION Methods Study area and initial data HYDROLOGICAL INFORMATION 279 reservoirs (>1 hm3) 679 Gauge stations (mean daily flow) 287 altered flow records

Study area and initial data HYDROLOGICAL INFORMATION Methods Study area and initial data HYDROLOGICAL INFORMATION Hydropower (HP; 16) Irrigation (IR; 16) Water supply (WS,7) Industrial (IN; 1) HP/IR (12) HP/WS (7) IR/WS (3) HP/IR/WS (4) 679 Gauge stations (mean daily flow) 66 Gauge stations 287 altered flow records

Hydrological classification of the fluvial network: Methods Hydrological classification of the fluvial network: PREDCIT-THEN-CLASSIFY PC1 PC2 ML30 ML90 75per sdMH7 sdMH30 nHPulse Frequency Magnitude Duration Timing Rate of change Mean flows Floods/ spates Droughts 84 Hydrologic Indices 221 Natural flow series Predicted PCs (Network) PCs (gauges) Environmental Data Hydrologic Classes Fitted Model (Random Forest) Clustering Environmental data

Hydrological alteration assessment Methods Hydrological alteration assessment 84 Hydrologic Indices PCs values of altered gauges (natural PCA) PCs values of natural gauges 66 Altered flow series PC2 PC1

Hydrological classification of the fluvial network Results Hydrological classification of the fluvial network PC1 – Magnitude & duration of low flows (+) PC4 – Magnitude spring flows (+) / winter flows (-) PC2 – Variability Magnitude & duration of high flows (+) / number of high flow pulses (-) PC5 - Magnitude spring flow & timing max flows (+) / Variability summer flows (-) PC3 – Variability of mean flows (+) / Magnitude & duration of high flows (-) PC6 – Variability of high flows events frequency 9-Class level classification

Var. of high flows frequency. Results Hydrological Class 1 Hydrological Class 1 PC1 vs PC2 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows High flows mag. Var. of high flows frequency. Low flows mag. Natural flow HP IR WS IN HP/IR HP IR WS IN HP/IR HP/WS IR/WS HP/IR/WS

Var. of high flows frequency. Results Hydrological Class 2 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows Low flows mag. High flows mag. Var. of high flows frequency. Natural flow HP HP/IR HP/WS IR/WS HP/IR/WS HP IR WS IN HP/IR HP/WS IR/WS HP/IR/WS

Var. of high flows frequency. Results Hydrological Class 3 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows Low flows mag. High flows mag. Var. of high flows frequency. Natural flow HP IR WS HP/IR HP/WS HP IR WS IN HP/IR HP/WS IR/WS HP/IR/WS

Var. of high flows frequency. Results Hydrological Class 4 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows High flows mag. Var. of high flows frequency. Low flows mag. Natural flow HP IR WS HP/IR/WS HP IR WS IN HP/IR HP/WS IR/WS HP/IR/WS

Var. of high flows frequency. Results Hydrological Class 5 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows High flows mag. Var. of high flows frequency. Low flows mag. Natural flow IR WS HP/WS IR/WS HP/IR/WS HP IN HP/IR HP/WS IR/WS HP/IR/WS

Var. of high flows frequency. Results Hydrological Class 7 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows Low flows mag. High flows mag. Var. of high flows frequency. Natural flow IR HP/WS HP WS IN HP/IR HP/WS IR/WS HP/IR/WS

Var. of high flows frequency. Results Hydrological Class 9 PC1 vs PC2 PC3 vs PC4 PC4 vs PC5 Var. high flows mag. Spring flow timing max. Spring flow n high pulses. Var. summer flows Winter flows Low flows mag. High flows mag. Var. of high flows frequency. Natural flow IR HP/IR HP WS IN HP/WS IR/WS HP/IR/WS

Conclusions Both the hydrological nature of the river and the activity influence the magnitude, the direction and the hydrological aspect altered by the reservoir. The use of hydrological classifications to assess the hydrological alteration at large spatial scales seems to be a useful tool The size of the reservoirs did not produced a clear and unequivocal effect on hydrological alteration This study must be completed with a larger number of altered series (e.g. flows released from reservoirs database)

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