Remote Sensing forManagement of Transboundary Aquifers in Africa

Remote Sensing forManagement of Transboundary Aquifers in Africa

More Information: www2.gaf.de/aquifer Email: aquifer@gaf.deAQUIFER Team, 03.07.2007

Users:Agence Nationale des Ressources Hydrauliques (Algeria)

General Water Authority (Libya)

Ministère des Mines, de l'Energie et de l'Eau (Mali)

Ministère de l'Hydraulique de l'Environnement et de la Lutte Contre la Désertification (Niger)

Federal Ministry of Water Resources (Nigeria)

Direction Générale des Ressources en Eaux (Tunisia)

African Partner Institutions :

Libyan Center For Remote Sensing and Space Science (Libya)

Centre National des Techniques Spatiales (Algeria)

Centre National de Télédétection (Tunisia)

AGRHYMET Regional Centre (Niamey - Niger)

European Consortium Partners:Joanneum Research (Austria)

SCOT CS (France)

Telespazio SpA (Italy)

University of Jena (Germany)

Vista GmbH (Germany)

AQUIFER - Partnership

Project Framework:

Initiation / Funding:

Prime Contractor:

User Coordinator:

In association withSahara and Sahel Observatory (OSS)

European Space Agency (ESA)

GAF AG

ESA TIGER Initiative

Sahara and Sahel Observatory (OSS)

Crop Water Demand of Irrigated Areas

Objectives:• Estimation of water needs for selected crops

and trees taking into account their morphology, phenology, growing rate and local meteorological parameters.

• Optimization of water quantity used for irrigation

• Reduce the over exploitation of the Aquifer

Product and Result

Methods applied and Data used

Objective

Prototype Areas:• PA1: Ouest des Zibans – Villages of

Doucen / Ouled Djellal, ALGERIA

• PA3: Gabès – TUNISIA

Benefits:• optimize the use of water for irrigation• optimize irrigation schedules• increase the plant’s health• improve groundwater management,• keep under control water abstraction,• reduce waste of water recourses for the

agricultural activities • reduce over exploitation of the aquifer

JOANNEUM RESEARCH Forschungsgesellschaft mbH (Austria) Institute of Water Resources Management

CROPWAT modelCROPWAT is a decision support system developed by the Land and Water Development Division of FAO for planning and management of irrigation. CROPWAT is meant as a practical tool to carry out standard calculations for reference evapotranspiration, crop water requirements and crop irrigation requirements, and more specifically the design and management of irrigation schemes. It allows the development of recommendations for improved irrigation practices and the planning of irrigation schedules. Input data: Reference Crop Evapotranspiration (Et0) calculated using the FAO Penman-Montieth equation based on decade/monthly climatic data: minimum and maximum air temperature, relative humidity, sunshine duration and windspeed; Rainfall data (daily/decade/monthly data); monthly rainfall is divided into a number of rain storm each month; Cropping Pattern consisting: planting date, crop parameters (including Kc values, stage days, root depth, depletion fraction) and the area planted (0-100% of the total area); Soil type: total available soil moisture, max.rooting depth, initial soil moisture depletion (% of total available moisture); Scheduling Criteria: e.g. 80 mm every 14 days, or irrigate to return the soil back to field capacity when all the easily available moisture has been used.

PA1: Ouest des Zibans – ALGERIA: Comparison between calculated crop water demand and real amount irrigated

Both in the basin of “Système d‘Aquifères Sahara Septentrional“ (SASS)

Model flowchart

Crop data

GIS

Land use/cover from RS

Monthly climate data

CROPWAT Model

Minimum air temperature

Maximum air temperature

Relative air humidity

Sunshine duration

Wind speed

Calculate ET0

Penman-Monteith

Crop coefficient

Stage days

Planting date

Root depth

Depletion fraction

Cropping pattern planting

Crop data file

Crop number

Planting date

Percentage of total area

Soil dataTotal available soil moisture

Max rooting depth

Max rain infiltration rate

Percentage of total available

moisture

Field Water Supply FWS

irrigation requirements

IWR

crop water requirements

CWR

monthly Rainfall data

Lat/Long/Altitude climate station

Water Abstraction Estimation for

Irrigation [l/s/ha]

Input modules:

Input parameters:

Model:

Output from Model:

Auxiliary Tool:

RESULTS:

Legend of Model

Input from other WP:

WAEI: Water abstraction estimation for irrigationWater abstraction estimation for irrigation is an estimation of the optimal amount of water to be extracted from the aquifer (or from other water sources) and applied to the irrigation scheme to satisfy the crop water demand during the growing season. The model “CROPWAT” (FAO) has been used to achieve this estimation. The land use/cover map has been used as base for the spatial distribution of water abstraction estimation that in this case has been calculated converting the values of IWR of each crop type from “millimeters per day” to “liter per second per hectare”. The values of the final map representing the water abstraction estimation is expressed as mean annual discharge per unit area in liter/second/hectare.

Mean annual water abstraction estimation for irrigation PA1: Ouest des Zibans - Algeria (2005) Comparison between AQUIFER and ANRH values

0

0.5

1

1.5

2

2.5

3

3.5

4

Mainly annual crops :Maize (Arid climate)Arboricolture : Table

grapes

Greenhouses withgarden produces

Palm trees: PalmIntercalary crops: Dry

Beans

Natural vegetation Other, including baresoils

Sum

l/s/h

a

Calculated crop water demandCROPWAT ModelReal amount irrigated from ANRH

CWR: Crop Water Requirements:PA1: PA3:

Cultures annuelles dominantes (maraichage, céréales/ arboriculture = Maize/Table grape

Maraîchage sous serres = Vegetables/Tomato

Palmier datier dominant/cultures interc. (autre arboriculture, maraîchage céréales,fourrage, légumineuses = Date Palm/Dry bean

Végétation naturelle de fond d’oued = Turf grass

Autre, dont terrains nus au sein de l’espace cultivé = Pasture

Palmier pur = Date Palm

Palmier/cultures interc.= Date palm/Carrot

Pistachier pur = Groundnut

Cultures de plain champ (Luzerne) = Alfalfa

Cultures de plain champ (Orge) = Barley

Cultures maraichage = TomatoOlivier pur = Olive Olivier /cultures interc.= Olive/Onion