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Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Page 1: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Ecosystem Functions and Services in IWRM

Road map of tools and assessmentsModels to aid

management decisions

Page 2: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Outline presentation

• Models as planning tools• Type of models• Basic Information• A water balance example• Discussion

Page 3: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Goal and objectives of the session

At the end of this session, participants will have a:

Basic knowledge about uses and limitations of models as planning tools,

Need for a good and reliable data base to validate the models and

Use of models to forecast environmental impacts and potential future scenarios.

Page 4: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Models

Some simple questions:

What is a model?

What do we need models for?

Can past event be a good indicator of future events?

Page 5: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Models

A model is an approximation of the reality.

It is an approximation, because the reality can be extremly complex and may never be fully understood.

Page 6: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Models

In the absence of perfect knowledge, the reality can be represented in a simplified way, by means of the system concept.

A system is a set of connected parts that form a whole.

The system response is determined by the interaction between the different parts in which the system is divided.

Page 7: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Models

By approximating the reality with the system approach, we can identify the impacts that changes, in the parts of system, will have in the system as a whole.

The information that we are getting is an approximation of the reality.

It is very important to define what aspects of the reality I need to know and evaluate.

Page 8: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Type of Models

Models can be:

Physical or abstract Deterministic or stochastic Lumped or distributed Steady or unsteady

Page 9: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Basic Information

In order to make good use of models, good and reliable information is needed.

To be able to forecast future impacts over the system, the model must be able to “forecast the past”.

Page 10: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Basic Information

Models have to be adjusted to the specific conditions and characteristics of the system that is being modelled.

This process is called calibration.

The calibration process needs good, reliable and long records of information.

Page 11: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Example

The water balance for the upper basin of the Tempisque River, Guanacaste, Costa Rica.

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Study Area

Provincia de Guanacaste, región Pacífico Norte de Costa Rica.

Cuenca alta del río Tempisque delimitada hasta la Estación fluviográfica Guardia (#741901, ICE).

Area total de la subcuenca: 955km2.

Estación Guardia

Liberia

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Characteristics of the study area

USO DEL AGUA

Agroindustria

Población

Medio Ambiente0

100

200

300

400

500

ENE

FEB

MAR AB

R

MAY JU

N

JUL

AGO

SET

OCT

NOV

DIC

(mm

)

ESCORRENTÍA

PRECIPITACIÓN

Page 14: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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General Goal of the Modelling Process

To develope a water balance model for the upper basin of the Tempisque River in order to be able to analyse diferent climatic scenarios and assess a minimum water flow for environmental purposes.

Page 15: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Model Information and Scope

The model estimates the principal processes of the hydrologi cycle on a monthly basis.

It uses precipitation, solar radiation and runoff data to keep a record of the soil moisture, the evapotranspiration and the groundwater recharge.

Onve the model is calibrated according to the physical, characteristics, climatic conditions, land use and soil types of the basin, it can be used to evaluate the impacts of changes in land use, climatic change or water withdrawal on the runoff pattern and water availability in the area.

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Model Information and Scope

Insufficient field information related to weather, hydrology, soil characteristics and land use.

Incomplete records.

Page 17: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Methodology

Page 18: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Hojas cartográficas del Instituto Geográfico Nacional (IGN), escala 1:50.000, con curvas de nivel a cada 20m.

Mapas de Zona de Vida de Costa Rica, Centro Científico Tropical (CCT), escala 1:200.000.

Mapas de Capacidad de Uso de la Tierra, Fundación Neotrópica, de escala 1:200.000.

Mapas de Uso del Suelo, Ministerio de Agricultura y Ganadería (MAG), 1992.

CONTINUA…

Methodology

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

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Methodology

Mapa Geológico de Costa Rica, Tournon & Alvarado, escala 1:200.000, 1997.

Datos mensuales de escorrentía y precipitación del Instituto Costarricense de Electricidad (ICE).

Datos mensuales de precipitación, temperatura y brillo solar del Instituto Meteorológico Nacional (IMN).

Datos mensuales de precipitación del Servicio Nacional de Riego y Avenamiento (SENARA).

Atlas de Costa Rica, 2000, del Instituto Tecnológico Costarricense.

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

Page 20: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Methodology

Identificación de inconsistencias: curvas de doble masa.

Estimación de datos faltantes de precipitación y temperatura y brillo solar: análisis de regresión o sustitución con el promedio del registro.

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

Page 21: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Methodology

Área de estudio: subcuenca definida hasta la estación fluviográfica Guardia (# 741901, ICE).

Delimitación a partir de la línea divisoria de aguas superficiales basandose en las hojas cartográficas del IGN escala 1:50.000.

Digitalización de la cuenca en un Sistema de Información Geográfica, con los equipos del Programa de Desarrollo Urbano Sostenible (ProDUS).

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

Page 22: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Methodology

Selección del período de calibración.

Precipitacion promedio.

Evapotranspiración potencial.

Capacidad de almacenamiento de agua del suelo.

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

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Methodology

Proceso de infiltración.

Factor de flujo base (k).

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

Page 24: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Methodology

ESTUDIO DE DISTINTOS ESCENARIOS DE PRECIPITACIÓN

Prueba estadística de los datos de precipitación anual.

Definición de rangos de precipitación para los escenarios seco, normal y húmedo.

Promedio de las condiciones climáticas de precipitación, temperatura y brillo solar para cada escenario.

Aplicación del modelo a cada escenario.

Recopilación de información básica

Preparación de la información meteorológica

Calibración del modelo

Delimitación de la cuenca

Cálculos preliminares

Aplicación del modelo

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Model Development

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Description of the model

Basado en el propuesto por Thornthwaite y Mather (1957).

Requiere el conocimiento de la precipitación (P), evapotranspiración potencial (ETP) y la capacidad de almacenamiento de agua del suelo (CAA).

El modelo desarrollado incluye la escorrentía directa (ED) y subsuperficial (ESS). Manejo diferente de la escorrentía subterránea o flujo base (FB).

P

FB

ETR

PERC ESS

ED

ES=ED+ESS+FB

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Conceptual Scheme

ESCORRENTÍA

EscorrentíaSubsuperficial

Escorrentía Directa

INFILTRACIÓN

PERCOLACIÓN

Estrato de rocas subterráneas

PRECIPITACIÓN

Estrato de suelo

Flujo Base

EVAPOTRANSPIRACIÓN

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Calibration of the model

0

50

100

150

200

250

300

350

400

1 11 21 31 41 51 61 71

Mes

Q (m

m)

Q medido

Q calculado

Coef. Corr. = 0.93R2 = 0.83

0

50

100

150

200

250

300

350

400

0 50 100 150 200 250 300

Q Medido

Q S

imul

ado

Período de calibración 1980-1985

Total de escorrentía calculada (mm) 4883

Total de escorrentía medida (mm) 5351

Porcentaje de error -8,7%

Coeficiente R2 0,8338

Page 29: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Precipitation Scenarios

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Seco Normal Húmedo

Pa<1400 1400<Pa<1800 Pa>1800

Años secos Años normales Años húmedos

1972 1968 1969 1976 1974 1970 1977 1975 1971 1983 1978 1973 1987 1980 1979 1990 1982 1981 1991 1984 1988 1992 1985 1995 1994 1986 1996 1997 1989 1998 2001 1993 1999

2000

Seco Normal Húmedo

Precipitation Scenarios

0

100

200

300

400

500

600

ENE FEB MAR ABR MAY JUN JUL AGO SET OCT NOV DIC

P (m

m)

P Escenario seco

P Escenario normal

P Escenario húmedo

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Escenarios de precipitación

CASO 1:

Escenario seco CASO 2:

Escenario normal CASO 3:

Escenario húmedo

Precipitación Annual (Pa) 1356;

(100%Pa) 1800;

(100%Pa) 2528;

(100%Pa)

Evapotranspiración potencial (ETP)

1636 1611 1587

Evapotranspiración real (ETR)

1072; (79%Pa)

1102; (61%Pa)

1174; (46%Pa)

ETR/ETP 0,66 0,68 0,74

Escorrentía Anual (Qa) 284;

(21%Pa) 698;

(39%Pa) 1354;

(54%Pa)

Picos en Caudal 22; 74; 36 62;176;137 156;283;319

Mes(es) de picos en el caudal

junio; octubre; noviembre

junio; septiembre; octubre

junio; septiembre; octubre

Flujo Base (FB) 233;

(82%Qa) 482;

(69%Qa) 837;

(62%Qa)

Escorrentía directa y subsuperficial (ED+ESS)

51; (18%Qa)

216; (31%Qa)

517; (38%Qa)

Déficit hídrico 564 508 413

0

50

100

150

200

250

300

350

E F M A M J J A S O N D

Q (

mm

)

ED+ESS

Flujo Base

0

50

100

150

200

250

300

350

E F M A M J J A S O N D

Q (

mm

)

ED+ESS

Flujo Base

0

50

100

150

200

250

300

350

E F M A M J J A S O N D

Q (

mm

)

ED+ESS

Flujo Base

Escenario Seco

Escenario Normal

Escenario Húmedo

Page 32: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Balance hídrico anual

Componente superficial

Componente subterráneo

20% 30% 40%

1350 1800 2500

PRECIPITACIÓN

1070 1100 1175

EVAPOTRANSPIRACIÓN

280 700 1350

ESCORRENTÍA

80% 70% 60%

Page 33: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

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Discussion

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Conclusiones

Cualquier herramienta de planificación del recurso hídrico requiere de una base de datos hidrometeorológica confiable; de ahí la importancia de invertir en una red de estaciones para la recopilación y un servicio que le proporcione mantenimiento y la haga disponible.

El modelo desarrollado presentó un buen ajuste entre los valores de caudal observados y los estimados, por lo que constituye una herramienta valiosa para la planificación y manejo del recurso hídrico en la cuenca alta del Río Tempisque.

Page 35: Ecosystem Functions and Services in IWRM Road map of tools and assessments Models to aid management decisions

Discussion

Why do we need models? What are we modelling? What information are we using to

validate the models? Is there enough information to validate

the model? How reliable are past events to

forecast future events?

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End