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European CommissionD. G. Environment

Halt Desertification in Júcar River Basin District

Precipitation Data & Scale Zones Report

January 2013. Exp. 07.032900/2011/614233/SUB/D1

Document Precipitation Data & Scale Zones ReportProject Halt Desertification in Júcar River Basin DistrictExp. 07.032900/2011/614233/SUB/D1Customer European Commission. D. G. EnvironmentElaborated by Vicente Ramírez

Elisa Vargas & Leticia RodriguezSupervised by Juan Gumbau

Version Draft Date version 23/01/2013Approved by xxx Date of approval xx/xx/xxxx

EUROPEAN COMMISSION. D. G. ENVIRONMENT

HALT DESSERTIFICATION IN JÚCAR RIVER BASIN DISTRICT

PRECIPITATION DATA & SCALE ZONES REPORT

Contents

1. Introduction...............................................................................................................................3

2. Data........................................................................................................................................... 3

2.1 Sources............................................................................................................................3

2.2 Geographic Data..............................................................................................................4

2.3 Preprocess of data.......................................................................................................... 5

2.3.1 ECRINS climatic data and Functional Elementary Catchments.................................5

2.3.2 EEA-WA zones..........................................................................................................7

2.3.3 SIMPA.......................................................................................................................9

2.3.4 PATRICAL..................................................................................................................9

2.3.5 AEMET......................................................................................................................9

2.3.6 AEMET+SAIH depurated...........................................................................................9

2.4 Series Database...............................................................................................................9

3. Contrast of series.....................................................................................................................10

3.1 Principal statistics over the period................................................................................10

3.2 Contrast of temporal series...........................................................................................11

3.3 Comparison of the distributions of values....................................................................14

3.4 Assessment of the uncertainty......................................................................................15

4. Conclusions..............................................................................................................................16

Annexes................................................................................................................................. 1

Annex 1 List of acronyms............................................................................................................2

Annex 2 Digital data................................................................................................................... 3

January 2013 EVREN i


HALT DESERTIFICATION IN JÚCAR RIVER BASIN DISTRICT


ii EVREN January 2013




1. Introduction

This report presents an analysis of rainfall data received from the EC in the framework of the Júcar River Basin District (JRBD) and makes a comparison with other precipitation series available in the JRBD or processed by us in the time period of January 2001 to December 2010.

As of 29/11/2012 two files were received by the EC for analysis. One of them with climatic data with spatial discretization by Functional Elementary Catchment (FEC) and another one with water balances with spatial discretization according to certain grouping of basins.

Discrepancies were found between the available climatic data, particularly in the variable precipitation, which will lead to major differences in other variables calculated from this one, as well as for in the results of water balances, which is the ultimate objective of the main works.

This study seeks to quantify the discrepancies observed in the variable precipitation in the requested time frame for conducting water balances corresponding to the years between 2001 and 2010 (both included). In addition, the aim is to obtain, by comparing different precipitation time series, an estimate of the uncertainty associated with climatic data, and, by derivation of this uncertainty, to find an estimate of the uncertainty associated with water balances.

Moreover, by quantifying the differences according to different sizes of the reference elements it will be apparent that the proposed FEC by the European Catchment and Rivers Network System (ECRINS) model are unduly small, causing large variations in the results among the different models in each element, being really difficult to gauge the results due to the lack of monitoring stations in the vast majority of the FECs. On the other hand, by reducing the area of comparison, an increased variability occurs among the data from different models, assuming that in small areas, such as a FEC, the uncertainty linked to each of the variables is greater, being impossible to reconcile balances within the same order of magnitude.

Furthermore, it is shown that the grouping of basins in water balances received from the EC does not correspond with a proper decomposition of the JRBD, as for climatic and functional reasons.

As a conclusion, it is proposed to work in the development of water balances with sub-basins whose discharge point are flow control elements (gauging stations), which will allow calibrating variables in water balance within these areas.

2. Data

2.1 Sources

To develop this study precipitation data have been obtained from the following information sources:

January 2013 EVREN 3




Table 1: Data sources

ENTITY1 TYPE Format Time range ObservationsCHJ (Júcar River Basin Authority)

PATRICAL modelMonthly raster with cell size of 1km2

January 2001 to September 2010

Reference model of the JRBD

AEMET Meteorological stations Monthly series 2001-2010

Low spatial frequency.Not publicly available since September 2011.

AEMET

Estimated precipitation by district from monthly summaries

Tables by RBD

September 2009 to December 2010

Tables of monthly summaries prior to September 2009 do not include the JRBD separately. They have been obtained to compare different results from the same starting data series in the same weather stations.

MAGRAMA

“Boletín Hidrológico” (hydrological bulletin)

Web queries

Disregarded since precipitation in the basin has been estimated with an arithmetic mean of the rain gauges located within the basin.

CEDEX-CEH SIMPA ModelMonthly raster with cell size of 1km2


CE-HJD

V_ClimFrom this point named as ECRINS

Access database with spatial subdivision by FEC


Version of April 2012Received 29/11/2012Values of September 2009 are null.

CE-HJD

Water AccountsFrom this point named as EEAWA

Excel bookJanuary 2001 to December 2008

Several grouped basins (Turia-Millars, Coastal 1, Coastal 2) and the Júcar River disaggregated (lower, medium-Cabriel, upper)Climatic data based on V_ClimReceived 29/11/2012

The data files of the six compared models are within the Original Data folder that accompanies this report.

2.2 Geographic Data

The folder Geographic Data includes the shape files used. In their associated tables, there is a field relating the nine Management Systems (abbreviated as SE from “Sistemas de Explotación”) of the JRBD. The projected information of these shapes is UTM Zone 30N (Datum WGS84).

1 In the annex List of acronyms there is a list of the main ones used in this report.

4 EVREN January 2013




Map 1: Management Systems of the Júcar RBD

2.3 Preprocess of data

2.3.1 ECRINS climatic data and Functional Elementary Catchments

For each FECs a field was added indicating to which Management System it belongs to, so later on, a weighted average of the precipitation value by area could be done.





In the data series of precipitation in the database v_clim (field rain) it was detected that values are null for all the FECs in the JRBD for month 9 of year 2009. The data of this year are not used when contrasting series, and they are not used either to calculate the correlation between different monthly series.

Also there are FECs with no data, but these have an insignificant area - except on Serpis and Marina-Alta Management System- and no further actions were taken. However, this information needs to be known for series comparisons purposes.

Other variables in v_clim database have no data for some FECs (represented in the following Table 2).

Table 2: Number of data variable available for the v_Clim database in the scope of the Júcar RBD for FEC which do not have the full set, except in the case of precipitation which is missing for all FEC is September 2009.

Number of records

ZHYD Temperature PrecipitationPotential

evapotranspiration

Actual evapotranspirat

ionE020145195 0 119 120 0E020146704 0 119 120 0E020146707 0 119 120 0E020147250 0 119 120 0E020147258 0 119 120 0E020147269 120 119 120 0E020147270 0 119 120 0E020147277 0 119 120 0E020147278 0 119 120 0E020147310 120 119 120 0E020148053 0 119 120 0E020148092 0 119 120 0E020148383 120 119 120 0E030150115 0 119 120 0E030150491 120 119 120 0W3C2000101 120 119 120 0W3C2000401 0 119 120 0W3C2000501 0 119 120 0W3C2001001 0 119 120 0W3C5000801 120 119 120 0W3C5001001 0 119 120 0W3C5001101 0 119 120 0

Finally, the FEC subdivisions are no coincident with boundaries of the JRBD, possibly because they are derived from a Sub-basin shape (see South-west and west of Map 2).





Map 2: FECs with no data are marked in red. The West and Southwest of the JRBD, show territory of the JRBD that on ECRINS belongs to other RBD.

2.3.2 EEA-WA zones

From the Excel received with Water Accounts, the precipitation data from de JRBD was extracted. This information is aggregated in some sort of set of sub-basins (see Table 3 and Map 3). The data are without geographical references, except for the total area of each zone. First, it was needed to associate these zones with the shape of sub-basins of the EEA. The area of the aggregated sub-basins was checked resulting in the areas shown in map SBdeEEAandSE.pdf in the folder Maps which is compared with the Management Systems.

The code used to distinguish between zones (see Table 3) is similar to the code in the field SB of the sub-basin data. The FEC data have also a code SB but is not complete and does not perfectly match with the other sources.





Table 3: EEA Water Accounts Zones

WSB0000196 : Jucar coastal: 1WSB0000197 : Jucar coastal: 2WSB0000198 : Jucar coastal: Turia, MillarsWSB0000199 : Jucar main - LowerWSB0000200 : Jucar main - Medium - CabrielWSB0000201 : Jucar main - Upper

In the south of the District, Vinalopó Basin there are significant differences between boundaries. Also, the boundaries in the south and in the west of the Jucar Basin do not match with the consolidated and official boundaries of the JRBD.

Map 3: Sub-basins and Water Accounts Zones vs. Management Systems





For comparison with Management Systems, the zones of the Jucar river was aggregated with the SBCode 999, for the other three zones the last three digits of the complete name was used (e.g. 196 for WSB0000196: Jucar coastal 1).

In the temporal series graphics, maps and other comparisons by Management System, the value of the precipitation for each Management System was taken from the zone that contains the Management System except in the case of the Júcar Basin where the value was weighted averaged from the three subzones.

2.3.3 SIMPA

The only pre-process made to the data of this model was clipped to the area of study, because the original data are for the whole Spanish territory.

This model takes in consideration the altitude in the estimated precipitation value.

2.3.4 PATRICAL

This is the model used by the JRBD officers as reference. It was not adapted at all.

The variables of this model will be used in the Water Account exercise.

2.3.5 AEMET

The value of the monthly data precipitation stations was spatially interpolated through krigging. The purpose of this model with an interpolation made by us is to contrast how the lack of information could affect the uncertainty of variable rainfall.

2.3.6 AEMET+SAIH depurated

This data was obtained through the same process as formerly described, adding the SAIH precipitation data existent in the JRBD and the neighbor districts. 435 stations were used (37 AEMET stations) of which 133 are inside of the limits of the JRBD (10 AEMET).

SAIH data from the JRBD are very depurated in origin and calibrated, but this is not the case for some districts that are nearby, having incorrect values due to typos, thousand symbol, and zero values when they must be nulls.

The SAIH data was depurated using a probabilistic approach. All the values above 800 mm/month were dropped as well as each with zero values that had a value of 10 mm/month in the average of the neighbor stations (from 50 km). The threshold of 10 mm/month was selected to have a 95% confidence of correct data by eliminating the zero values, after evaluating the distributions of precipitation in one station with zero value in AEMET stations versus the average of the neighboring stations.

2.4 Series Database

The monthly precipitation series used and compared in the territory of each Management System are in the database PreciptByExplotationSystem in the table StatsSEYearMonth in the folder Series Database.





Table 4: Field descriptor of the table with distinct precipitation data series

Field DescriptionTypeOfCalc Type of calculation to obtain the data: "Desc"->"unknown", "KRG"->"krigging 12

points spherical 150 km max"TypeOfData One of the compared six modelsSE Management SystemDYear YearDMonth MonthPm Mean Precipitation in the Management SystemPt Total Precipitation in the Management System

The folder Results contains all charts and graphics by Management System, and for the total of the Júcar RBD, in PDF and JPG format. The most significant figures are used also in this report.

The maps with contrast of distinct models for selected months are in the folder maps.

3. Contrast of series

3.1 Principal statistics over the period

Since PATRICAL only has data until September 2010 the period considered for statistics was 2001-2009 inclusive. As it will be shown below, EEA-WA data is equivalent to ECRINS, since it takes values of the former. Because of that EEA-WA was not compared in correlations or in averaging models, not affecting then that EEA-WA has no values over 2009.

Table 5: Annual precipitation by model

Annual precipitation (mm) Model

Year

AEM

ET

AEM

ET+

SAIH

dep

ECRI

NS2

012

EEAW

A

PATR

ICAL

SIM

PA

Mea

nm

odel

s2

std

std/

Mea

n m

odel

s

rang

e

2001 375 407 360 361 436 454 407 39 10 942002 465 540 453 454 563 596 523 62 12 1432003 449 546 364 365 582 629 514 107 21 2652004 443 526 395 397 560 602 505 85 17 2072005 294 319 262 261 342 369 317 41 13 1072006 371 411 331 331 436 463 402 52 13 1322007 467 521 420 419 565 580 511 67 13 1592008 474 506 503 504 610 629 545 70 13 1552009 428 466 265 494 512 433 99 23 2462010 492 544 469 586 523 53 10 117

Mean 2001-2008 417 472 386 386 512 540 466 64 14 154Mean with available complete annual data 426 479 382 386 510 542 468 64 14 159

2Mean models, standard deviation and range do not uses data from EEAWA





Correlation of the temporal data between series is shown in Table 6 for the entire JRBD and by Management System. Correlations above 0.9 between PATRICAL and ECRINS can indicate bad data on ECRINS3 or insufficient nearby stations. In Mijares-Plana de Castellón the correlation between ECRINS and all other models is deficient (except for EEAWA that is the same data but it is not equal to 1 because of zoning used on WA) meaning that is possible there bad data exist. In other Management System the correlation is deficient but acceptable with AEMET, maybe this is explained because the same data origin and amount of data are used. In general, when the surface of the Management System is small the correlation between and the other models is worst, especially with those which have more density of data.

Table 6: Correlation between data series. Period between 2001 and 2008, for JRBD and by Management System

Júcar RBD Cenia-Maestrazgo

Mijares-Plana de Castellón Palancia-Los Valles

Turia Júcar

Serpis Marina Alta

Marina Baja Vinalopó-Alacantí

3.2 Contrast of temporal series

Figure 1 and Figure 2 show the evolution of the monthly values of distinct models. Besides of mentioned problem of September 2009, it is clear that in many months there are significant dissimilarities between ECRINS and other models.

Generally, ECRINS values are smaller than those of the other models. The difference with PATRICAL shown with shaded green when PATRICAL is greater, and red in the opposite case.

For the cases August 2001, July 2003, July 2005, July 2006, data on ECRINS is zero or near zero. This is because maybe the data are forced to zeros or distance spatial interpolation is relatively short for the stations used – it seems that was the case for AEMET stations due the similitude of both models.

3 Tables are in folder results/Graf/tbCorr_NameOf Exploitation System





Figure 1: Evolution of variable precipitation function of data origin for the entire JRBD, showing the difference between PATRICAL and ECRINS (2001-2005)

Figure 2: Evolution of variable precipitation function of data origin for the entire JRBD, showing the difference between PATRICAL and ECRINS (2006-2010)

For the related case of Mijares-Plana de Castellón Management System where the correlation was indicated poor, Figure 3 and Figure 4 show that ECRINS are above the rest of models more frequently than in others Management





Systems4. Despite this, the mean of period 2001-2008 remains far below -575 mm for PATRICAL and 488 for ECRINS.

Figure 3: Evolution of variable precipitation function of data origin for Mijares-Plana de Castellón Management System, showing the difference between PATRICAL and ECRINS (2001-2005)

Figure 4: Evolution of variable precipitation function of data origin for Mijares-Plana de Castellón Management System, showing the difference between PATRICAL and ECRINS (2006-2010)

3.3 Comparison of the distributions of values

Considering the distribution respect the District and for the full period, the differences are no significant (Figure 5).

4 All the graphs by Exploitation System are in folder Results/Graf





Figure 5: Comparison of the distribution values for JRBD for the full period.

The same colors and positions of the different models in Figure 5, are used in the following figures.

Figure 6: Comparison of the monthly distribution values of each model in the Júcar Basin

Figure 6 shows great differences between ECRINS-EEAWA and the rest of models in the Júcar Management System for all months except May and November. Besides the problem mentioned of September 2009, the maximum value on September of ECRINS-EEAWA is similar to the lowest of all other models.

For others Management System the differences are also observed (see Results/Graf).

The monthly precipitation distribution from the PATRICAL model considered over the period (that will be used on the Water Account Exercise) is shown on Figure 7.





Figure 7: Monthly distribution of PATRICAL values over the period for the JRBD

3.4 Assessment of the uncertainty

Usually, the uncertainty of measures of precipitation in meteorological stations has negative bias due to losses (evaporation). Various common methods of measure in automatic stations have a negative bias also due to precipitation not counted by the mechanism. In automatic stations usually the value was corrected through calibration. In any case, there exists an uncertainty associated with the measure. This uncertainty depends on used apparatus, conservation and calibration. In all the cases treated uncertainty was unknown, but it can be estimated at about 10% with no more precise information.

In the interpolation process to extend measures to all the territory the uncertainty also grows. One possibility to estimate the uncertainty derived from this process comes from the raster variance resulting of the krigging. In this case, we have three series, one for AEMET stations, second a series for AEMET+SAIH with more density stations and third, one that is like the second series but dropping anomalous data. Supposing that data in each cell of the raster is uncorrelated with respect the cells in the same Management System –which is clearly false but allows us to take an inferior bound- we can estimate the variance over the area of each Management System and take an average over the period of the percentage of the mean variance over the mean precipitation. This inferior bound rounds 50% averaging over the full period.

Estimating the uncertainty from the dispersion between the models (see Table 7), this is about 25% for the majority of Management System and 20% for the full JRBD. In three Management Systems (Serpis, Marina Alta y Marina Baja) the dispersion between models is markedly higher than other zones. In these, there is a lag of data in ECRINS (FECs without rainfall data) and possibly also bad estimations.





Table 7: Assessment of the uncertainty of precipitation over 2001-2009 period, averaging models monthly and by Management System

Statistics of the set of models over 2001-2009

period

Mean precip.

Pm

Mean std. between models

σ

Uncert.u=σ/Pm Max u in monthly data

Max monthly absolute difference between

PATRICAL and ECRINS5

Management System mm mm % % Year Month mm Year MonthCenia-Maestrazgo 550 145 26 18 2007 5 90 2004 3Mijares- Plana de Castellón 521 136 26 17 2008 6 92 2007 4Palancia – Los Valles 489 122 25 20 2006 11 90 2007 4Turia 464 97 21 43 2003 10 54 2007 10Júcar 444 92 21 26 2008 5 71 2008 10Serpis 613 263 43 16 2005 11 322 2004 12Marina Alta 644 357 55 7 2001 6 423 2007 10Marina Baja 499 186 37 32 2007 5 155 2004 12Vinalopó-Alacantí 346 81 23 42 2009 4 48 2009 3Júcar RBD 463 94 20 38 2005 9 53 2008 10

4. Conclusions

Errors detected in the series of climate data currently do not recommend the use of ECRINS for performing water balances in the basin. Also, for the available time period, ECRINS series have relatively little success in the case of the JRBD giving values significantly lower than those observed. Furthermore, in the case of this river basin, better models exist that can be used.

Moreover, the geographical definitions of FEC have errors, and thus do not agree with the official boundaries of the river basin itself. FECs have also been found with an area less than 1 km2 (a non-practical size).

Moreover, it has been shown that the smaller the area the higher the scattering between models, and higher the uncertainty for the precipitation variable. It is therefore proposed not to work with small surface units, requiring in addition, whenever possible, that the closure of these areas is made by a gauging station, which will allow calibrating the balance between the different variables within that area. In addition, the study areas should be large enough so that the random involved variables in the calculations tend to statistical equilibrium.

It should be noted that the exercise of SEEA-Water was originally developed at the country level, thus trying to move the calculations to entities as small as the FEC and monthly scale does not seem adequate. It is desirable however, that areas to be studied in relatively large watersheds, or where management sub-systems may exist, are conveniently subdivided, but always bearing in mind that they should represent economic uses taking place in those subdivisions. Grouping for instance, basins between the Management Systems-Maestrazgo Cenia to Turia, together with coastal areas between them, leads to group territories without climatic or water management connection. Thus, the results that may arise from the water balances exercise can not only be inconclusive in this area, but will not highlight the real problems of the territory or be useful to compare results from different studies.

Therefore, we believe that the division and/or grouping of areas to develop water balances should be a proposal from, or at least agreed with, representatives of the river basin, since they are the ones who know better their management and planning frameworks.

5 Excluding 2009/09 where ECRINS has no data.





A similar analysis of this report for the variable temperature would yield analogous results in terms of accuracy and dispersion across models. In particular, existing models that take into account the altitude at each point for the calculation of the temperature and precipitation variables have a better accuracy (e.g. PATRICAL and SIMPA models). This improved accuracy in both variables leads to better quantification of derived variables such as potential and actual evapotranspiration.

In particular, it is recommended to work with climatic data contrasted locally by the authorities of each region until a model sufficiently calibrated at local scale is available. If that were not the case, useful water balances cannot be expected for territories smaller than the one representative of the used climatic model. Thus, as part of our work to develop water balances, we will use precipitation and real evapotranspiration data from the PATRICAL model.





ANNEXES

January 2013 EVREN A1




Annex 1 List of acronyms

Acronym MeaningCHJ Confederación Hidrográfica del Júcar (Júcar River Basin Authority)DHJ Demarcación Hidrográfica del Júcar (Júcar River Basin District –JRBD-)MAGRAMA Ministerio de Agricultura, Alimentación y Medio Ambiente (Spanish Ministry

of Agriculture, Food and Environment)EC European CommissionHJD Halting Desertification in the Júcar River BasinSAIH Sistema Automático de Información Hidrológica (Hydrologic Information

Automatic System)FEC Functional Elementary Catchment

A2 EVREN January 2013




Annex 2 Digital data

All the data, graphs and tables used are attached to this report on compressed files.

January 2013 EVREN A3

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