41 research outputs found
Climate Modification of Dry Desert Air by a Large Irrigation Project
Climatic changes caused by the evapotranspiration
of large amounts of irrigation
water may be important in irrigation scheduling,
weather forecasting and the management of irrigated
farmland. Results from previous studies
are often in disagreement as to the magnitude of
climatic modification by irrigation. Some
studies show only minimal changes (Fritschen and
Nixon, 1967, Fowler and Helvey, 1974) and others
show sizeable modifications (Davenport and
Hudson, 1967). Beebe (1974) reports that severe
storms as indicated by tornado's are more prevalent
over irrigated land in Texas. A recent
statistical report (Schickendanz, 1976) shows
rainfall increases, temperature anomalities, and
hail increases, all caused by irrigation.
Schickendanz work covered a very large area in
the Great Plains of the United States. Previously
reported studies differ greatly in size of
area involved and objectives. The studies reported
here had the objective of showing the
possible climate modification caused by a large
irrigation project in Idaho surrounded by a nonirrigated
sagebrush grass desert
Changes in Climate and Potential Evapotranspiration Across a Large Irrigated Area in Idaho
Ground level climatic measurements
were taken along a 50
km transect going from dry sagebrush
land into the center of a large
irrigated area in southern Idaho.
Measurements in May, when the
desert area was dry, indicated
that climatic changes across the
transect were minimal. In August,
when the desert was obviously very
dry, air temperatures decreased,
vapor pressure increased, and
windspeed was reduced about
40 percent within the irrigated
area. The results demonstrate
that any weather service agency or
group must consider the distance
from dry surroundings when selecting
sites that are to be representative of
climatic conditions over irrigated
fields
Water Requirements (Chapter 6)
The main objective of irrigation is to provide plants with sufficient water
to prevent stress that may cause reduced yield or poor quality of harvest
(Haise and Hagan, 1967; Taylor, 1965). The required timing and amount of
applied water is governed by the prevailing climatic conditions, crop and
stage of growth, soil moisture holding capacity, and the extent of root
development as determined by type of crop, stage of growth, and soil
Irrigation Management -- Water Requirements and Water Balance
This paper seeks to discuss irrigation water requirement estimates in the
light of current practice, important developments during the 1970's, significant
research and future research and applications of that research. Each of
these are elaborated in more detail in the text of this paper.
A major addition to the science and art of estimating irrigation water requirements
has been to replace the often ambiguous "potential evapotranspiration"
with "reference crop evapotranspiration". In the past decade a series of experiments
relating irrigation water applications to crop yield now permit a
much better economic analysis of the use of water for irrigation. The estimation
of monthly irrigation water requirements was facilitated, particularly
for varying climatic conditions with the United Nations publication "Crop
Water Requirements" by Doorenbos and Pruitt (1977).
Estimation of daily water requirements for purposes of irrigation scheduling
has been refined by the development of an albedo model and a wind function
for the Penman method, that is variable throughout the season, Wright (1981).
Several western states are experiencing lawsuits or other legal deliberations
involving seasonal irrigation water requirements because of conflicts between
groups of water users or water right transfers from agriculture to industry
or municipal use. Irrigation scheduling continues to be refined from the
standpoints of predicting ET, verifying yield conditions and other factors
like production and peak pumping power reduction. Future research probably
will include emphasis on breeding crops that require less water, refinements
on the relationships between yields and water consumption, refinements in
methods of estimating irrigation water requirements, and the development of
irrigation schemes that minimize water and energy requirements.
For other methods and more detail the reader is referred to sources such as
Doorenbos and Pruitt (1977), Jensen (1974), Barman. et al. (1981)
Changes in Climate and Potential Evapotranspiration Across a Large Irrigated Area in Idaho
Ground level climatic measurements
were taken along a 50
km transect going from dry sagebrush
land into the center of a large
irrigated area in southern Idaho.
Measurements in May, when the
desert area was dry, indicated
that climatic changes across the
transect were minimal. In August,
when the desert was obviously very
dry, air temperatures decreased,
vapor pressure increased, and
windspeed was reduced about
40 percent within the irrigated
area. The results demonstrate
that any weather service agency or
group must consider the distance
from dry surroundings when selecting
sites that are to be representative of
climatic conditions over irrigated
fields
Water Requirements (Chapter 6)
The main objective of irrigation is to provide plants with sufficient water
to prevent stress that may cause reduced yield or poor quality of harvest
(Haise and Hagan, 1967; Taylor, 1965). The required timing and amount of
applied water is governed by the prevailing climatic conditions, crop and
stage of growth, soil moisture holding capacity, and the extent of root
development as determined by type of crop, stage of growth, and soil
Irrigation Management -- Water Requirements and Water Balance
This paper seeks to discuss irrigation water requirement estimates in the
light of current practice, important developments during the 1970's, significant
research and future research and applications of that research. Each of
these are elaborated in more detail in the text of this paper.
A major addition to the science and art of estimating irrigation water requirements
has been to replace the often ambiguous "potential evapotranspiration"
with "reference crop evapotranspiration". In the past decade a series of experiments
relating irrigation water applications to crop yield now permit a
much better economic analysis of the use of water for irrigation. The estimation
of monthly irrigation water requirements was facilitated, particularly
for varying climatic conditions with the United Nations publication "Crop
Water Requirements" by Doorenbos and Pruitt (1977).
Estimation of daily water requirements for purposes of irrigation scheduling
has been refined by the development of an albedo model and a wind function
for the Penman method, that is variable throughout the season, Wright (1981).
Several western states are experiencing lawsuits or other legal deliberations
involving seasonal irrigation water requirements because of conflicts between
groups of water users or water right transfers from agriculture to industry
or municipal use. Irrigation scheduling continues to be refined from the
standpoints of predicting ET, verifying yield conditions and other factors
like production and peak pumping power reduction. Future research probably
will include emphasis on breeding crops that require less water, refinements
on the relationships between yields and water consumption, refinements in
methods of estimating irrigation water requirements, and the development of
irrigation schemes that minimize water and energy requirements.
For other methods and more detail the reader is referred to sources such as
Doorenbos and Pruitt (1977), Jensen (1974), Barman. et al. (1981)