The document discusses hydrological concepts including flow duration curves, meteorological stations, indices used to analyze streamflow, weirs, and the relationship between upstream and downstream areas. It provides definitions and examples of flow duration curves, exceedance probability, flashiness, and how afforestation and cultivation can impact the hydrological response of different biomes. Graphs and diagrams are included to illustrate hydrological responses, streamflow variability, and the impact of land use changes.

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SEVENTH CLASS

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OBJECTIVES
• To polish up the preliminar power point presentation
• To become familiar with hydrological vocabulary.
• To analyse the flow duration curve in order to be able to
explain the graph.
SIXTH CLASS

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http://www.visualdictionaryonline.com/earth/meteorology/meteorological-station.php
METEREOLOGICAL STATION

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WorldClim - Global Climate Data
Free climate data for ecological modeling
WorldClim is a set of global climate layers (gridded climate data)
with a spatial resolution of about 1 km2. These data can be used for
mapping and spatial modeling.
Source: http://www.worldclim.org/

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Because only a limited number of catchments are
equipped with a metereological station, reference
evapotranspiration was estimated using Worldclim
temperature data.
Correlations between multiple local rain gauges were
used to detect and correct errors to fill data gaps and
to obtain reliable averaged values.
HOW DO WE FILL ABSENCE OF DATA?

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INDICES RELATED TO METEOROLOGICAL FEATURES
• ETo
• SINDX
• DAYP0
• PVAR
INDICES RELATED TO STREAMFLOW FEATURES
• RR
• QVAR
• R2FDC
• IRH
• DLQ75
• QHQ25
INDICES USED IN OUR STUDY

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• Precipitation is summarized in the seasonality index SINDX
• Annual ratio of days with zero precipitation DAYP0
• Daily rainfall variability PVAR
• Runoff ratio RR
• Daily flow variability QVAR
• Slope of the flow duration curve R2FDC
• The hydrological regulation index IRH
• Average low flow duration below the 25th flow percentile DLQ75
• Average high flow duration above the 75th flow percentile DHQ25
INDICES USED IN OUR STUDY

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What is a weir?
A weir is a concrete or masonry structure which is
constructed across the open channel (such as a river)
to change its water flow characteristics. Weirs are
constructed as an obstruction to flow of water.
These are commonly used to measure the
volumetric rate of water flow, prevent flooding and
make rivers navigable.
https://theconstructor.org/water-resources/what-is-weir-types-flow-over-weirs/11873/

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https://www.openchannelflow.com/blog/weir-plate-materials
What is a weir?

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Rectangular weir:
https://theconstructor.org/water-resources/what-is-weir-types-flow-over-weirs/11873/
Triangular weir:
Trapezoidal weir:

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Checkgates
Checkgates are sometimes larger than turnout gates and are typically used
to control flow on community ditches.
Checkgates involve more than just a gate as they must span the width of
your ditch and allow for erosion control on the downstream side.
Our turnout gates can be easily incorporated into a checkgate and we will
help you understand the additional steps needed.
http://www.cementirrigationgates.com/gate-sizes-and-prices.html

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Turnout gates are usually located in the side of a ditch but can
also be used as checkgates on small ditches.
Our engineered corners allow you to combine gates and
panels to create distribution boxes or other custom
installations.
Turnout Gates
http://www.cementirrigationgates.com/gate-sizes-and-prices.html

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https://www.researchgate.net/figure/Interacting-components-of-upstream-downstream-linkages-
related-to-the-natural_fig2_265848170
Interacting components of upstream-downstream linkages related to the
natural (hydrological) environment and associated human systems.

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https://ecologicalprocesses.springeropen.com/articles/10.1186/s13717-014-0019-4
The terms `upstream' and `downstream' are also relative, for example the transition
zone is downstream in relation to the headwaters but upstream in relation to the
flood plains.
UPPERSTREAM AND DOWNSTREAM

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https://www.sciencedirect.com/science/article/pii/S0022169414000183
Variation of monthly precipitation and direct runoff (right) generation
DESCRIBE THE GRAPH

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FLOW DURATION CURVES (FDC)
Hydrographs are relatively easy to understand
The data from hydrographs can be used to produce flow duration
curves (FDCs) These provide more information.
River and stream flows will seasonally fluctuate depending on
precipitation amounts or on other upstream factors that could affect
flow such as weirs or other flood control measures.
Source: https://www.youtube.com/watch?v=QEjKuPa3VTo

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Exceedance Probability
Sometimes a hydrologist may need to know what the chances are
over a given time period that a flood will reach or exceed a
specific magnitude. This is called the probability of occurrence or
the exceedance probability.
Exceedance probability = 1 - (1 - p)n
http://stream1.cmatc.cn/pub/comet/HydrologyFlooding/flood/comet/hydro/basic/Floo
dFrequency/print_version/02-statistical_rep.htm

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Source: https://www.researchgate.net/figure/Hydrological-response-of-different-Andean-biomes-in-a-
year-The-left-vertical-axis_fig1_307011721
Hydrological response of different Andean biomes in a year. The left vertical axis corresponds to
precipitation and the right vertical axis to streamflow. The flow duration curves and annual water
yield are aggregated over the complete catchment monitored periods. Notice that the time series
show different years

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https://www.researchgate.net/figure/Impact-of-pine-afforestation-on-the-hydrological-response-of-a-
paramo-b-jalca-and_fig5_307011721
Impact of pine afforestation on the hydrological response of (a) páramo, (b) jalca and (c) puna. The black lines
represent the reference natural catchments and the grey lines their pairs. The high-resolution 30-day time series
sections present comparable precipitation events and their correspondent streamflow responses. The flow duration
curves and annual water yield are aggregated over the complete catchment monitored periods

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Impact of cultivation on the hydrological response of (a) páramo and (b) puna. The black lines represent the
reference natural catchments and the grey lines their pairs. The high-resolution 30-day time series sections
present comparable precipitation events and their correspondent streamflow responses. The flow duration curves
and annual water yield are aggregated over the complete catchment monitored periods
Source: https://www.researchgate.net/figure/Impact-of-cultivation-on-the-hydrological-response-
of-a-paramo-and-b-puna-The-black_fig4_307011721

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Flashiness reflects the frequency and rapidity of short
term changes in stream flow in response to storm
events.
Streams that rise and fall quickly are considered
flashy.
It is difficult to detect changes with such a limited
dataset.
FLASHINESS
https://oehha.ca.gov/media/downloads/ecotoxicology/document/flashiness2015.pdf

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FLOW DURATION CURVES FDC FACTS
The slope between 33% and 66% of the FDC is
commonly used as an indicator of hydrological
regulation
A steep slope is associated with high flashiness
response to input precipitation, whereas a flatter curve
represents buffered behaviour and larger storage
capacity