ii. Hydrobiological (NMx –Technical Annex 5)

6.2. Methodologies

3. Objective

4. Field of application

5. Normative references of special interest for the NMx

6.3. Environmental flows proposal content

1. Background

2. Scientific principles or foundations

Sergio Salinas

Program Officer Conservation of aquatic ecosystems

WWF-México

ssalinas@wwfmex.org

Eugenio Barrios

Director, Water Program

WWF-México

ebarrios@wwfmex.org

For further information please contact:

Poff N.L., J.D. Allan, M.B. Bain, J.R. Karr, K.L. Prestegaard, B. Richter, R. Sparks and J. Stromberg. 1997. The natural regime: a new paradigm for riverine conservation and restoration. BioScience 47:769-784.

Davies S.P. y Jackson S.K. 2006. The Biological Condition Gradient: A Descriptive Model for Inter-preting Change in Aquatic Ecosystems. Ecological Applications: Vol. 16, No. 4 pp. 1251–1266.

USEPA. 2005. Use of Biological Information to Better Designated Aquatic Life Uses in State and Tribal Water Quality Standards: Tiered Aquatic Life Uses.

1

2

WWF-FGRA ALLIANCE MODEL:

Systematization of results and national experiences; international experiences reviewed

20 diagnostic workshops and EF with participation of more than 100 experts (water users, academics, government employees, communities and NGO)

Three Mexican river basins

Figure 1. Process to develop NMx from WWF-FGRA Alliance model

Figure 2. Scientific principles of the NMx

Figure 5. EF regime (low flows and high pulses) projected in a hypothetical period of 10 years

COMPONENTS OF HYDROLOGICAL REGIME

Maintenance of habitat diversity and connectivity X XXXX

X

X

XXX

X

X

X

XX

Drou

ght e

pisod

es (r

ed)

Seaso

nal p

attern

of lo

w flo

ws (g

reen)

High p

ulses

regim

e and

flood

s (blu

e)

Maintenance of appropiate hydrodynamic conditions Maintenance of seasonal habitat diversitySynchronization of environmental patternsControl of presence and abundance of speciesGood physical-chemical conditions of water and sedimentsImprovement of geomorphological dynamic conditionsControl and improvement of hydrological processes

ECOL

OGICA

L FUN

CTIO

NS

Caud

al (m

3 / se

g)

1800

1-feb

1-mar

1-abr

1-may

1-jun

1-jul

1-ago

1-sep

1-oct

1-nov

1-dic

1-ene

1600

1400

1200

1000

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600

400

200

0

R IVER IN NATURAL CO NDITIONS1

2

34

56

S TRE S S OR GRADIENT

BIOL

OGICA

L CON

DITI

ON

Natural

Degrated

Low High

Minimal loss of species

Some sensitive species maintained but notable replacement by more tolerant taxa

Some replacement of sensitive-rare species

Tolerant species show increasing dominance

Native or natural condition

Severe alteration of structure and function

NATURAL FLOW PARADIGM1

BIOLOGICAL CONDITION GRADIENT 2

Hydrological BasinsEnvironmental objective

Administrative hydrological region*Peninsula of Yucatan aquifers**International limit

*Hydrological basins in white are still in analysis to obtain their environmental objectives**Environmental objective according aquifers information in Peninsula of Yucatan

Environmental objective

Ecological importance• NPA's• Conservation priorities• Ramsar sites

Water pressure• Allocations among water users Eco

logica

l imp

ortanc

e

Water pressureCRITERIA Low Medium High Very High

Very High A A B CHigh A B C D

Medium B C C DLow B C D D

Figure 3. Conceptual model, criteria matrix and environmental objectives map

Figure 4. EF regime using reference values

01-Jan 01-Feb 01-Mar 01-Apr 01-May 01-Jun 01-Jul 01-Aug 01-Sep 01-Oct 01-Nov 01-Dec

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Flow

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MEAN MONTHLY FLOW VERY GOOD GOOD MODERATE DEFICIENT DAILY AVERAGE FLOW EF chosen

6. General specifications

6.1. Environmental objectives

Institutions involved in the Mexican Norm project

Figure 6. Methodological framework for EF analysis through physical habitat modeling according to preferences of certain species.

Selection of critical points

Field trip and initial recognition selection 1D/2D

2nd Survey (Spring - Summer)Hydrometry of the reach

Additional survey(Validation and capture of additional data)

Construction of habitat models

Calibration of habitat models

Habitat mapped Selection of the reach

Connectivity validation Temporal series of habitat

Minimum flows range recommendation

Obtaining of curves HPU-Q

1st Survey (Winter-Spring)Topography of riverbed and riversideHydrometry of the reach

Results

Generation of specific preference curves

1st SurveyWinter - SpringAdults - Alevin

2nd SurveySpring - Summer

Adults - Alevin - Young

3rd SurveySummer - Autumn

Young - Adults

Generation of preference curves

Figure 7. Conceptual model for an holistic methodology development

Preliminary activities

Selection of reference sites

Discussion workshopsFirst proposal of EF

Integration of proposal in final

report

Determination study units in

the basin

Information• Hydrology

HydraulicsGeomorphologyWater qualityGeohydrologyBotanyIctiologyAquatic macroinvertebratesSociology

• • • • • • • b •

• Current ecological stateEcological importance and sensitivityCurrent water pressure stateEnvironmental objectivesHydrological sceneriesProposal of EF agreed

•

• •••

Federal Electricity Commission, National Water Commission, Natural Protected Areas Commission, National Commission for Knowledge and Use of Biodiversity, Institutes of Biology and Engineering of the National University of Mexico, Mexican In-stitute of Water Technology, National Institute of Ecology, Sec-retariat of Environment and Natural Resources, The Nature Conservancy and World Wildlife Fund for Nature, Inc. Mexico Program.

Generation of previsionable

curves and comparission with literature

Generation of preference curves and comparission

with experts

Since 2004, the Alliance conformed by World Wildlife Fund for Nature (WWF) and Gonzalo Río Arronte Foundation, I.A.P. (FGRA), in collaboration with National Water Commission (CONAGUA) and others federal agencies, as well as academic institutions, Non-Governmental Organizations (NGO), water users and rural com-munities, has developed three different proposals of environmental flows (EF) in river basins with different conservation, water pressure and management con-texts: i) Conchos river in Chihuahua; ii) Copalita-Zimatán-Huatulco rivers in Oaxaca; and iii) San Pedro Mezquital river in Zacatecas, Durango and Nayarit. From 33 sites analyzed in detail in the three river basins, in 73% of the cases EF occurs under current conditions; in 21%, management requires regulation in the conditions of water extraction and in operation of infrastructure; and only in 6% is necessary to make adjustments in user’s water allocation. These results were systematized for the proposed Mexican Norm (NMx) (Figure 1).

Two core principles are followed to determine the hydrological requirements of aquatic ecosystems, and therefore they are the foundation of the EF Mexican Norm (Figure 2). These principles allow to identify valid EF methodologies and set a nor-mative framework up.

Any given methodology to determine EF regime will be valid if it leads to practice of the key scientific principles, for example:

• It must allow for understanding of the ecological significance of each flow regime component, and generate proposals from a functional point of view, for its conservation or reestablishment • The proposal must consider the natural hydrological variability for ordinary (low flows) and extraordinary (high pulses and floods) conditions • It recognizes that an aquatic ecosystem modifies its features in response to an increase in stress levels, and therefore, it allows adjustment to pro- posals to the environmental objectives or conservation of the river.

To establish the technical procedures and specifications for determining EF regime in streams or national water bodies in a hydrological basin.

Water allocation, infrastructure, or any other work that involves water transfer among basins and the like, which requires an Environmental Impact Assessment. All streams and water bodies whose availability agreements published in the Offi-cial Government Gazette did not considered flows for aquatic ecosystems conser-vation.

NOM-011-CONAGUA-2000. Conservation of the resource of water – which estab-lishes the specifications and methodology for determining the mean annual avail-ability of the nation’s waters.

NOM-059-SEMARNAT-2010. Environmental protection – Wildlife species of flora and fauna native to Mexico – Categories of risk and specifications for its inclu-sion, exclusion or change – List of species in risk.

The described methods are considered as minimum technical requirements and do not exclude the implementation of complementary or more precise methods.

The EF regime should be determined based on the associated environmental ob-jective, according to the basin’s ecological importance and water pressure (NMx– Technical Annex 1), whether surface streams, water bodies of diverse kinds, or as part of the associated aquifer’s natural discharge, to conserve and protect the environmental conditions and promote ecological balance.

Environmental objectives represent the ecological state that is intended to be ob-tained or preserved in the basin. They establish the relationship between the value of conservation (ecological importance) and its implication for the produc-tive uses of water (water pressure) (Figure 3).

i. Hydrological (NMx – Technical Annex 2, 3 y 4) Application: Without conflicts for water use and with hydrological regime

unaltered (Figure 4) • Procedure based on reference values as percentages ranges of mean

annual runoff and taken to a monthly scale

Applicacion: With presence of water infrastructure (i.e. hydropower plants) and altered hydrological regime (Figure 5), the method should define:• Seasonal low flows regime for wet, average, dry and very dry hydro-

logical conditions • Intra-annual (Type I) and inter-annual (low and mid magnitude – Type II

and III, respectively) high pulses regimes with their respective attri-butes of magnitude, duration frequency, timing, and rate of change

Habitat simulation models to project the physical habitat and its changes due the flows. It has the purpose of quantifying habitat preferences of species, or one in particular that could be taken as an objective (Figure 6). Frequently in these models hydraulic variables are used in the determina-tion of the connectivity of rivers, floods and channel capacities. Among the most used models are: • Instream Flow Incremental Methodology (IFIM)• Physical Habitat Simulation System (PHABSIM)

iii. Holistic (NMx – Technical Annex 6)

Highly recommended for those cases where detailed proposal of EF is needed or required due to a river’s complexity, social conflicts or difficulties. Focused on particularities of the zone of interest, and specifically, identify the ecologi- cal significance of hydrological regime components and their relationship with the basin’s ecological importance and the impact on water uses (Figure 7). Methodologies of this kind are:

• Building Block Methodology (BBM) • Downstream Response to Impose Flow Transformation (DRIFT) • Benchmarking • Ecological Limits Of Hydrologic Alteration (ELOHA)

EF Mexican Norm procedure results will be presented according to gauging sta-tions located in the river basin (headquarters or highlands, midlands and lowlands) and at each sub-basin discharge. The report should have the following content:

i. Description of the hydrological basin ii. Selection and characteristics of the sub-basin iii. Environmental flows per basin a) Description of the methodology used, justification and preliminary de- termination of environmental flows b) Reference sites and proposal of environmental flows iv. Annexes. Technical data and other detailed information of each analyzed reference site

MEXICAN NORM (NMX) THAT ESTABLISHES THE PROCEDURE FOR ENVIRONMENTAL FLOW DETERMINATION IN HYDROLOGICAL BASINS

ENVIRONMENTAL OBJECTIVE "A"

Natural daily flow Natural monthly flow Environmental flowHIGH PULSES

Type III

Type I

Type II

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1 2 3 4 5 6 7 8 9 10

Flow

(m3 /

sec)