A new approach to rainfall recording and analysis

Authors: Tan, S. K., and Chiew, Y. M.
Source: Water Management of the Amazon Basin, (35-44)
Editors: Braga, Benedite P. F., Jr., and Fernandez-Jauregui, Carlos A.
Date: August 1991

Notes

The article makes ackowledgement of the recent advances in remote sensing of rainfall, saying that for most of the world this technology is not available
For those areas, the authors procede to discuss smaller advances in more traditional methods of rainfall measurement

The authors argue for fixed-event domain recording over fixed-time recording

Fixed-time recording records the amount of rainfall over a set interval of time

This method produces a large number of extraneuous zeros in data sets

Fixed-event recording records the time interval over which a set amount of rain falls

This method eliminates the large amount of extraneous zeros, making data sets leaner and more manageable.
Since the article is dated 1991, I am not sure of the validity of the authors arguments. Data storage due to recent advances in computer is much more economical than in the past. Nevertheless, the authors present an interesting alternative
The authors then present details on a computing device which could fulfill this task, no information on cost is provided

Applications of hillslope process hydrology in forest land management issues: the tropical north-east australian experience

Authors: Bonell, Mike
Source: Water Management of the Amazon Basin, (45-82)
Editors: Braga, Benedite P. F., Jr., and Fernandez-Jauregui, Carlos A.
Date: August 1991

Notes

Effect of land-use change

Poorly managed land-use change can compact soil and destroy surface macropores, dramatically reducing soil water infiltration capacity, thereby increasing runoff

This leads to reduced recharge of soil and groundwater stores, leading to diminished dry season flows

Conversion of forests to grasslands increases delayed flow (dry-weather flow)

During extended dry periods, converted grasslands will have higher groundwater levels due to decreased evapotranspiration

The sum od these two effects determines the net change in groundwater levels

Runoff rates highly correlated to rain intensity

Also related to Ks value, slope,

Overland flow dominates humid and semi-aric environments (low Ks)

Water and salt balances of the Bolivian Amazon

Authors: Roche, M. A., et al.
Source: Water Management of the Amazon Basin, (83-94)
Editors: Braga, Benedite P. F., Jr., and Fernandez-Jauregui, Carlos A.
Date: August 1991

Notes

Rainfall data

Madre de Dios basin:

2500-7000mm on the andean flank

1800-2500mm on the plain
2380mm average

Beni River basin

800-1000mm on summit in andean part
400mm in upper part of hot valleys (Yungas) in andean part
350-500mm in most protected zones - behind upper summiits of the Cordilleera
1720mm in main part of andean basin
1650-2000mm in plains, with mean of 1810mm
1755mm average

Mamoré andean basin

480mm in the most semi-arid zone
6000mm at the foot of the andes
750mm average in Rio Grande basin
3000mm on the oriental watersheds
800mm in Amazon plain
3000mm in Ichilo basin
1900mm at head of Madeira river
800-1900mm toward north
1000-4000mm toward west
1850mm average

Itenez River basin

900mm in the south
18000mm in the east
1900mm in the northeast
1375mm average

Upper Madeira basin

1705mm average

Evapotranspiration

Two methods of evaluation

The water balance, that is the differernce between precipitation and discharge
Formulas
Differences of two methods are 0-14%
Evapotranspiration remains the most difficult evalutation of the water balance

Data

610mm in the semi-arid Rio Grande basin
1520mm in the Orthon River basin
780mm in Andean part of Beni River basin
1220mm in oriental basins of Mamoré River
800mm in the Bolivian andean part of the upper Madeira River basin
63-68% of precipitation , 33-37% is runoff

Water resources management for energy generation purposes in streams presenting strong seasonal flow variations - planning aspects -

Authors: Petry, Bela, and Grull, Doron
Source: Water Management of the Amazon Basin, (95-105)
Editors: Braga, Benedite P. F., Jr., and Fernandez-Jauregui, Carlos A.
Date: August 1991

Notes

Three fundamental questions to use of river for hydroelectric power

Need to provide adequate river regulation and construct hydropower developments along important streams characterized by large seasonal variation without excessive environmental impacts

The question of reservoir storage capacities and flooded areas becomes important

Distance to be covered by energy transmission if many of the best hydropower sites are located deep into the amazon

Consider environmental impacts of implementation of lines as well as high cost

Inter-regional exchange of energy and the differences in hydrologic cycles between drainage basins in different regions of the country require revision of planning practices to incorporate the variation in of energy generation capabilities, their time patterns, the possibility of thermal complementation

Possible climatic impacts of amazonia deforestation

Authors: Nobre, Carlos A.
Source: Water Management of the Amazon Basin, (245-260)
Editors: Braga, Benedite P. F., Jr., and Fernandez-Jauregui, Carlos A.
Date: August 1991

Notes

Amazonina rainforest is highly efficient in recycling water vapor back into the atmosphere
Different types of vegetation might not be as efficient in maintaining high rates of evapotranspiration
Great diffuculty in modeling the effects of deforestation on climate

Studies have been too abstract to predict regional changes
Until resolution is at 1000km, regional changes cannot be predicted

Table comparing average rainfall, transpiration, evapotranspiration, and runoff results of various stuides (page 255)

Climate variability and its effects on amazonian hyrdology

Authors: Molion, Luiz Carlos Baldicero
Source: Water Management of the Amazon Basin, (261-274)
Editors: Braga, Benedite P. F., Jr., and Fernandez-Jauregui, Carlos A.
Date: August 1991

Notes

Hydologic cycle is the major singel heat source for th atmosphere in the form of latent heat, which is realeased through condensation of atmospheric moisture
Three scales of rainfall producing mechanisms

Continental / large scale

Solar radiation absorbed at the surface is primarily used for evaporating water (latent heat, 80-90% of energy) and for heating the air (sensible heat, balance of energy)
Intertropical Convergence Zone in the Atlantic (ITCZA), the convergence of Northern and Southeren hemisphere trade winds

Sinoptic scale (1000km)

Southern hemisphere cold fronts or frontal systems which penetrate into Amazonia any time of the year

Winter systems generally characterized by a sharp 15-20º temperature decrease which lasts 3-5 days

Generally NW-SE oriented and cross the coast between latitudes 15-25ºS during summer

Northern hemisphere frontal systems may also have similar effect

Subsinoptic scale (500-1000km)

Instability or squall lines of the atmosphere

Highest frequency is in July
Occassionaly propagate inland

Maybe due to convergence of sea breeze
May also be associated with waves in the trade wind field tiggerred by frontal systems deep penetraton over the subtropical Atlantic

Meso scale (100km)

Convective cell and clusters of Cbs

Produce intense precipitation of short duration in random locations

Microscale (1-10km)

Small convective cells

Form during the morning hours and precipitation around 14-15hrs local time

Interannual variability

El niño phenomenon contributes to this

Note: Thank you to Professor Raphael Bras for the loan of Water Management of the Amazon Basin.