NREM 461 Dr. Greg Bruland

Size: px

Start display at page:

Download "NREM 461 Dr. Greg Bruland"

Christina Kennedy
5 years ago
Views:

1 Water Conservation NREM 461 Dr. Greg Bruland 1

2 Global water distribution (ga.water.usgs.gov/edu/watercyclesummary.html, g g y 2006). 2

3 I. Water Conservation o A. Broad clim. patterns controlled by precip, air & ocean circ., topo 1. Precip. a. abundant in some areas, others consistently arid i. Mt. Wai ale ale, Kaua i: 650 in (16,50 cm) yr -1 vs Global Precipitation (Wright) b. 3

4 2. Global air circ. a. air rises in equatorial regions (suns rays cause warm temps) descends at poles b. high-alt. winds take air from equator poles, low alt. winds vice versa c. movement of air forms 3 cells in N & S hemispheres i. middle cell rotates counter to other 2 d. zones bet N & S lat predominantly arid ii. 4

5 Global Air Circulation (Purves et al) 5

6 3. Ocean currents a. Ocean circ. effects climate thru transfer of thermal energy i. Iceland milder temps than expected due to Global ocean currents (Cech 2003) 6

7 4. Role of topo. features a. air cools as it rises to go over a mountain causing precip. (windward) b. rain shadow on leeward side where air tends to be dry, warm as it descends i. Prevalent in Rain shadow effect (Purves et al.) 7

8 B. Drought 1. In terms of crop prod., drought: whenever lack of H 2 O reduces growth & yield of staple crops in a region a. atmospheric drought: combo of low humidity, high temp, & high winds cause high transpiration rates b. soil drought: H 2 O supply diminished by low soil moisture due to low precip, low permeability, or low storage capacity 8

9 2. Plants dvpd. strategies to cope w/ drought: a. escape: geminate, grow, produce seed during brief life span b. evade: have large root systems, low transpiration rates, mechanisms to reduce leaf area or close stomata c. endure: have massive H 2 O storing organs or shed leaves & go dormant d. What class do crops fall into? 9

10 C. Combating Drought 1. Problem arise due to irregular rainfall in space & time 2. What happens to rainfall? 10

11 3. Interception: most of this H 2 O evaporates 4. Runoff a. variable in space i. ranges from 0-75% b. variable in time i. usu. higher in later part of storm, as 11

12 5. Evap.: often > than 50% of annual precip, i. higher in darker soils 6. Trans.: diff. to measure, represents consumption of H 2 Of for plant growth i. Ranges from 2.7 in in. 7. Deep percolation: H 2 O moves below plant roots & into GW system i. Humid areas largest losses = ii. Dryland areas largest losses = 12

13 D. Ways to runoff 1. infiltration rate-keep veg & residues on top of soil 2. use crop rotations, & mulches to keep fields covered 3. use contour tillage & terraces to trap H 2 O, infiltration 4. improve soil structure w/ residue, mulch tillage, chemical conditioners 5. trap runoff in ponds, reservoirs, create microcatchment pits Straw mulch Farm pond Microcatchments in Malawi 13

14 Hydrolyzed y polyacrylonitrile (HPAN) or Krillium 14

15 Polyacrylamide (PAM): synthetic H 2 O-soluble polymer made from monomers of acrylamide that binds soil particles together. Once soil particles suspended in H 2 O are bound together by PAM, they settle out, so it is more difficult to wash them out of a field. Type of PAM: Soil Binder* (granular PAM) Liquid PAM Soil PAM Power Blocks* (PAM cubes) Cost/UnitofPAM: of $1.86/pound $16.49/gallon $2.54/pound 15

16 Zai pits or tassa in Niger Microcatchment system in Mexico in rainy season 16

17 E. Ways to Evap. & Trans. 1. Evap: use of no-till, crop res. & mulches a. Mulches i. Vegetative: ii. Non-vegetative: 2. Trans: control of weeds & volunteer plants 17

18 Use of polyethylene plastic film as mulch: Shown to: yield, weed control, soil temp, evap. Use of plastic mulch w/ Use of plastic mulch w/ Use of green plastic mulch 18

19 F. Water harvesting & summer fallow 1. water harvesting: method of collecting & concentrating ti H 2 O in small area to grow plants that require more H 2 O than normal precip. provides a. done w/ catchment structures, artificial depressions, trenches, poltethylene film & asphalt coverings b. 19

20 Water harvesting dams Systems to infiltration of runoff Rooftop rainwater harvesting & storage systems c. 20

21 21

22 Modern residential rooftop rainwater collection & storage system 22

23 Integrated rooftop & paved surface rainwater collection, filtration, & storage system 23

24 2. summer fallow: practice of leaving a field w/o a crop during growing season to store H 2 O for future crops a. 24

25 G. Ways to loss of soil water: 1. plant crop only when reasonable chance of successful prod. 2. grow efficient crops: drought resistant spp or hybrids 3. plant & cultivate w/ timeliness & precision

SOIL AND THE HYDROLOGIC CYCLE

GEOLOGY 408/508 SOIL AND THE HYDROLOGIC CYCLE CHAPTER 6 Brady & Weil, Rev. 14th ed. THE HYDROLOGIC CYCLE (FIGURE 6.2) WATER BALANCE EQUATION Watershed - an area of land drained by a single stream system