AGROHYDROLOGYAGROHYDROLOGY

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Prof. Dr. Tahir SarwarProf. Dr. Tahir Sarwar

CONTENTSCONTENTSBLOCK 1: INTRODUCTION TO AGROHYDROLOGYBLOCK 1: INTRODUCTION TO AGROHYDROLOGY

1.11.1 IntroductionIntroduction1.21.2 Organisation of the courseOrganisation of the course1.31.3 Water depths and volumesWater depths and volumes1.41.4 Water balanceWater balance

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BLOCK 2: COLLECTION, PROCESSING AND INTERPRETATION OF WEATHER BLOCK 2: COLLECTION, PROCESSING AND INTERPRETATION OF WEATHER DATADATA

BLOCK 2A: COLLECTION OF METEOROLOGICAL DATABLOCK 2A: COLLECTION OF METEOROLOGICAL DATA2.12.1 IntroductionIntroduction2.22.2 Weather stationsWeather stations2.32.3 HumidityHumidity2.42.4 WindWind2.52.5 Solar radiationSolar radiation2.62.6 TemperatureTemperature2.72.7 PrecipitationPrecipitation2.82.8 EvaporationEvaporation

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CONTENTSCONTENTSBLOCK 2B: PROCESSING AND INTERPRETATION OF METEOROLOGICAL DATABLOCK 2B: PROCESSING AND INTERPRETATION OF METEOROLOGICAL DATA

2B.12B.1 Average of mean valuesAverage of mean values2B.22B.2 RainfallRainfall

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BLOCK 3: COMPUTATION OF THE REFERENCE CROP EVAPOTRANSPIRATION BLOCK 3: COMPUTATION OF THE REFERENCE CROP EVAPOTRANSPIRATION (ET0)(ET0)3.13.1 IntroductionIntroduction3.23.2 Water and plant growthWater and plant growth3.33.3 Direct measurement of evapotranspirationDirect measurement of evapotranspiration3.43.4 Indirect methods for determining ET0Indirect methods for determining ET0

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BLOCK 4: CROP WATER REQUIREMENTSBLOCK 4: CROP WATER REQUIREMENTS4.14.1 IntroductionIntroduction4.24.2 Determination of the crop coefficient (Kc)Determination of the crop coefficient (Kc)4.34.3 Computation of crop water requirementsComputation of crop water requirements4.44.4 Factors affecting ETcropFactors affecting ETcrop

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CONTENTSCONTENTS

BLOCK 5: NET IRRIGATION REQUIREMENTSBLOCK 5: NET IRRIGATION REQUIREMENTS5.15.1 IntroductionIntroduction5.25.2 Determination of effective rainfallDetermination of effective rainfall5.35.3 Ground water contributionGround water contribution

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BLOCK 6: LEACHING REQUIREMENTSBLOCK 6: LEACHING REQUIREMENTS6.1 6.1 IntroductionIntroduction6.26.2 SalinitySalinity

Questions and assignmentsQuestions and assignmentsFINAL CASE-STUDY ON IRRIGATION REQUIREMENTSFINAL CASE-STUDY ON IRRIGATION REQUIREMENTS

Block 1: Introduction to AgrohydrologyBlock 1: Introduction to Agrohydrology

HydrologyHydrology is the science which studies the circulation and is the science which studies the circulation and distribution of water near the surface of the earth: through distribution of water near the surface of the earth: through the atmosphere (evaporation, transpiration, precipitation), the atmosphere (evaporation, transpiration, precipitation), on the earth’s surface (rivers, oceans, small streams, on the earth’s surface (rivers, oceans, small streams, surface runoff), and below the ground surface (ground surface runoff), and below the ground surface (ground water flow, drainage). water flow, drainage).

AgrohydrologyAgrohydrology studies only that part of the hydrologic studies only that part of the hydrologic cycle which is relevant for agricultural purposes and deals cycle which is relevant for agricultural purposes and deals with the circulation of water through the plant, atmosphere with the circulation of water through the plant, atmosphere and the soil. A schematic presentation of the and the soil. A schematic presentation of the agrohydrologic cycle is shown in Figure i. 1;agrohydrologic cycle is shown in Figure i. 1;

The central unit in the agrohydrologic cycle is the part of The central unit in the agrohydrologic cycle is the part of the soil which contains crop roots. the soil which contains crop roots.

Figure 1.1 Agrohydrologic CycleFigure 1.1 Agrohydrologic Cycle

1.3 WATER DEPTHS AND VOLUMES1.3 WATER DEPTHS AND VOLUMES

1.3 WATER DEPTHS AND VOLUMES1.3 WATER DEPTHS AND VOLUMES

1.3 WATER DEPTHS AND VOLUMES1.3 WATER DEPTHS AND VOLUMES

1.3 WATER DEPTHS AND VOLUMES1.3 WATER DEPTHS AND VOLUMES

Volume of water in agricultureVolume of water in agriculture

Figure 1.2 Schematic representation of the amount of rainfall expressed in depth (millimetre)

Figure 1.3 A soil moisture content of 150 Figure 1.3 A soil moisture content of 150 millimetre per metre (mm/m)millimetre per metre (mm/m)

Example 1. Calculation of a volumeExample 1. Calculation of a volume

1.4 WATER BALANCE1.4 WATER BALANCE

QUESTIONS AND ASSIGNMENTSQUESTIONS AND ASSIGNMENTS

QUESTIONS AND ASSIGNMENTSQUESTIONS AND ASSIGNMENTS