scholarly journals Identifying Functional Flow Linkages Between Stream Alteration and Biological Stream Condition Indices Across California

2022 ◽  
Vol 9 ◽  
Author(s):  
Ryan Peek ◽  
Katie Irving ◽  
Sarah M. Yarnell ◽  
Rob Lusardi ◽  
Eric D. Stein ◽  
...  
Keyword(s):  
Large Scale ◽  
Environmental Flows ◽  
Condition Index ◽  
Benthic Invertebrate ◽  
Dry Season ◽  
Environmental Data ◽  
Biological Assessment ◽  
Wet Season ◽  
Pulse Flow ◽  
Stream Condition

Large state or regional environmental flow programs, such as the one based on the California Environmental Flows Framework, rely on broadly applicable relationships between flow and ecology to inform management decisions. California, despite having high flow and bioassessment data density, has not established relationships between specific elements of the annual hydrograph and biological stream condition. To address this, we spatially and temporally linked USGS gage stations and biological assessment sites in California to identify suitable paired sites for comparisons of streamflow alteration with biological condition at a statewide scale. Flows were assessed using a set of functional flow metrics that provide a comprehensive way to compare alteration and seasonal variation in streamflow across different locations. Biological response was evaluated using the California Stream Condition Index (CSCI) and Algal Stream Condition Index (ASCI), which quantify biological conditions by translating benthic invertebrate or algal resources and watershed-scale environmental data into an overall measure of stream health. These indices provide a consistent statewide standard for interpreting bioassessment data, and thus, a means of quantitatively comparing stream conditions throughout the state. The results indicate that indices of biological stream condition were most closely associated with flow alteration in seasonality and timing metrics, such as fall pulse timing, dry-season timing, and wet season timing. Magnitude metrics such as dry-season baseflow, wet season baseflow, and the fall pulse magnitude were also important in influencing biological stream conditions. Development of ecological flow needs in large-scale environmental programs should consider that alteration to any of the seasonal flow components (e.g., dry-season baseflow, fall pulse flow, wet-season baseflow, spring recession flow) may be important in restructuring biological communities.

scholarly journals Clarifying regional hydrologic controls of the Marañón River, Peru through rapid assessment to inform system-wide basin planning approaches

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Alice F. Hill ◽  
Robert F. Stallard ◽  
Karl Rittger
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
Rapid Assessment ◽  
Rapid Change ◽  
Dry Season ◽  
Environmental Data ◽  
Wet Season ◽  
River Continuum ◽  
Hydropower Development ◽  
Address Data

We use remote sensing to enhance the interpretation of the first baseline dataset of hydrologic, isotopic and hydrochemical variables spanning 620 km of the upper Marañón River, in Andean Peru, from the steep alpine canyons to the lower lying jungle. Remote, data-scarce river systems are under increased hydropower development pressure to meet rising energy demands. The upstream-downstream river continuum, which serves as a conduit for resource exchange across ecosystems, is at risk, potentially endangering the people, environments, and economies that rely on river resources. The Marañón River, one of the final free-flowing headwater connections between the Andes and the Amazon, is the subject of myriad large-scale hydropower proposals. Due to challenging access, environmental data are scarce in the upper Marañón, limiting our ability to do system-wide river basin planning. We capture key processes and transitions in the context of hydropower development. Two hydrologic regimes control the Marañón dry-season flow: in the higher-elevation upper reaches, a substantial baseflow is fed by groundwater recharged from wet season rains, in contrast to the lower reaches where the mainstem discharge is controlled by rain-fed tributaries that receive rain from lowland Amazon moisture systems. Sustainability of the upper corridor’s dry-season baseflow appears to be more highly connected to the massive natural storage capacity of extensive wetlands in the puna (alpine grasslands) than with cryospheric water inputs. The extent and conservation of puna ecosystems and glacier reservoirs may be interdependent, bringing to bear important conservation questions in the context of changing climate and land use in the region. More generally, this case study demonstrates an efficient combined remote sensing and field observation approach to address data scarcity across regional scales in mountain basins facing imminent rapid change.

Migratory Labour from North-Wester Nigeria

Africa ◽  
1957 ◽  
Vol 27 (3) ◽  
pp. 251-261 ◽  
Author(s):  
R. Mansell Prothero
Keyword(s):  
Large Scale ◽  
Source Area ◽  
Dry Season ◽  
Labour Migration ◽  
Agricultural Activity ◽  
Wet Season ◽  
The North ◽  
The People ◽  
Limited Scale ◽  
Opening Paragraph

Opening ParagraphReaders of Africa will be well aware of population migration as a characteristic feature of a continent where movement between one part and another is largely unrestricted as compared with the more settled parts of the world. There is much evidence of large-scale tribal migrations in the past, of the age-old seasonal wanderings of herders, and of recent labour migration to centres of mineral and industrial production, the last particularly in Central and South Africa. Information is more limited concerning the features of labour migration in West Africa at the present day. In general it is thought that migrants leave their home areas, after the harvest at the commencement of the dry season, to seek work elsewhere for a period of from three to six months and then return to take up farming with the commencement of the next rains. The major source area for these migrants is to the north of the tenth parallel where the wet season is concentrated into a period of about four months, thus severely restricting agricultural activity. Cultivation during the dry season is possible only on a very limited scale. There is thus a considerable period of the year when the primary economic activity of the people is not possible. It is logical that they should seek work elsewhere.

scholarly journals Large-scale vertical velocity, diabatic heating and drying profiles associated with seasonal and diurnal variations of convective systems observed in the GoAmazon2014/5 experiment

2016 ◽  
Vol 16 (22) ◽  
pp. 14249-14264 ◽  
Author(s):  
Shuaiqi Tang ◽  
Shaocheng Xie ◽  
Yunyan Zhang ◽  
Minghua Zhang ◽  
Courtney Schumacher ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Large Scale ◽  
Early Morning ◽  
Dry Season ◽  
Diurnal Variations ◽  
Wet Season ◽  
Convective Systems ◽  
Heating Source ◽  
Seasonal And Diurnal Variations ◽  
Eddy Fluxes

Abstract. This study describes the characteristics of large-scale vertical velocity, apparent heating source (Q1) and apparent moisture sink (Q2) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) that were conducted from 15 February to 26 March 2014 (wet season) and from 1 September to 10 October 2014 (dry season) near Manaus, Brazil, during the Green Ocean Amazon (GoAmazon2014/5) experiment. The derived large-scale fields have large diurnal variations according to convective activity in the GoAmazon region and the morning profiles show distinct differences between the dry and wet seasons. In the wet season, propagating convective systems originating far from the GoAmazon region are often seen in the early morning, while in the dry season they are rarely observed. Afternoon convective systems due to solar heating are frequently seen in both seasons. Accordingly, in the morning, there is strong upward motion and associated heating and drying throughout the entire troposphere in the wet season, which is limited to lower levels in the dry season. In the afternoon, both seasons exhibit weak heating and strong moistening in the boundary layer related to the vertical convergence of eddy fluxes. A set of case studies of three typical types of convective systems occurring in Amazonia – i.e., locally occurring systems, coastal-occurring systems and basin-occurring systems – is also conducted to investigate the variability of the large-scale environment with different types of convective systems.

scholarly journals Large-Scale Vertical Velocity, Diabatic Heating and Drying Profiles Associated with Seasonal and Diurnal Variations of Convective Systems Observed in the GoAmazon2014/5 Experiment

2016 ◽  
Author(s):  
Shuaiqi Tang ◽  
Shaocheng Xie ◽  
Yunyan Zhang ◽  
Minghua Zhang ◽  
Courtney Schumacher ◽  
...  
Keyword(s):  
Vertical Velocity ◽  
Large Scale ◽  
Early Morning ◽  
Dry Season ◽  
Diurnal Variations ◽  
Wet Season ◽  
Convective Systems ◽  
Heating Source ◽  
Seasonal And Diurnal Variations ◽  
Eddy Fluxes

Abstract. This study describes the characteristics of large-scale vertical velocity, apparent heating source (Q1) and apparent moisture sink (Q2) profiles associated with seasonal and diurnal variations of convective systems observed during the two intensive operational periods (IOPs) of the Green Ocean Amazon (GoAmazon2014/5) experiment, which was conducted near Manaus, Brazil in 2014 and 2015. The derived large-scale fields have large diurnal variations according to convective activity in the GoAmazon region and the morning profiles show distinct differences between the dry and wet seasons. In the wet season, propagating convective systems originating far from the GoAmazon region are often seen in the early morning, while in the dry season, they are rarely observed. Afternoon convective systems due to solar heating are frequently seen in both seasons. Accordingly, in the morning, there is strong upward motion and associated heating and drying throughout the entire troposphere in the wet season, which is limited to lower levels in the dry season. In the afternoon, both seasons exhibit weak heating and strong moistening in the boundary layer related to the vertical convergence of eddy fluxes. A set of case studies of three typical types of convective systems occurring in Amazonia – i.e., locally-occurring systems, coastal-occurring systems and basin-occurring systems – is also conducted to investigate the variability of the large-scale environment with different types of convective systems.

Seasonal–Interannual Variation and Prediction of Wet and Dry Season Rainfall over the Maritime Continent: Roles of ENSO and Monsoon Circulation

2016 ◽  
Vol 29 (10) ◽  
pp. 3675-3695 ◽  
Author(s):  
Tuantuan Zhang ◽  
Song Yang ◽  
Xingwen Jiang ◽  
Ping Zhao
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Southern Oscillation ◽  
Dry Season ◽  
La Niña ◽  
Monsoon Circulation ◽  
Wet Season ◽  
Maritime Continent ◽  
La Nina

Abstract The authors analyze the seasonal–interannual variations of rainfall over the Maritime Continent (MC) and their relationships with El Niño–Southern Oscillation (ENSO) and large-scale monsoon circulation. They also investigate the predictability of MC rainfall using the hindcast of the U.S. National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). The seasonal evolution of MC rainfall is characterized by a wet season from December to March and a dry season from July to October. The increased (decreased) rainfall in the wet season is related to the peak-decaying phase of La Niña (El Niño), whereas the increased (decreased) rainfall in the dry season is related to the developing phase of La Niña (El Niño), with an apparent spatial incoherency of the SST–rainfall relationship in the wet season. For extremely wet cases of the wet season, local warm SST also contributes to the above-normal rainfall over the MC except for the western area of the MC due to the effect of the strong East Asian winter monsoon. The CFSv2 shows high skill in predicting the main features of MC rainfall variations and their relationships with ENSO and anomalies of the large-scale monsoon circulation, especially for strong ENSO years. It predicts the rainfall and its related circulation patterns skillfully in advance by several months, especially for the dry season. The relatively lower skill of predicting MC rainfall for the wet season is partly due to the low prediction skill of rainfall over Sumatra, Malay, and Borneo (SMB), as well as the unrealistically predicted relationship between SMB rainfall and ENSO.

scholarly journals A newly discovered wildlife migration in Namibia and Botswana is the longest in Africa

Oryx ◽  
2014 ◽  
Vol 50 (1) ◽  
pp. 138-146 ◽  
Author(s):  
R. Naidoo ◽  
M. J. Chase ◽  
P. Beytell ◽  
P. Du Preez ◽  
K. Landen ◽  
...  
Keyword(s):  
Large Scale ◽  
Dry Season ◽  
Wet Season ◽  
Anthropogenic Pressures ◽  
Ecological Processes ◽  
Serengeti Ecosystem ◽  
Straight Line ◽  
Land Use Transformation ◽  
Wildlife Migration ◽  
Connochaetes Taurinus

AbstractMigrations of most animal taxa are declining as a result of anthropogenic pressures and land-use transformation. Here, we document and characterize a previously unknown multi-country migration of Burchell's zebra Equus quagga that is the longest of all recorded large mammal migrations in Africa. Our data from eight adult female zebras collared on the border of Namibia and Botswana show that in December 2012 all individuals crossed the Chobe River and moved due south to Nxai Pan National Park in Botswana, where they spent a mean duration of 10 weeks before returning, less directly, to their dry season floodplain habitat. The same southward movements were also observed in December 2013. Nxai Pan appeared to have similar environmental conditions to several possible alternative wet season destinations that were closer to the dry season habitat on the Chobe River, and water availability, but not habitat or vegetation biomass, was associated with higher-use areas along the migratory pathway. These results suggest a genetic and/or cultural basis for the choice of migration destination, rather than an environmental one. Regardless of the cause, the round-trip, straight-line migration distance of 500 km is greater than that covered by wildebeest Connochaetes taurinus during their well-known seasonal journey in the Serengeti ecosystem. It merits conservation attention, given the decline of large-scale ecological processes such as animal migrations.

Dietary overlap between cattle and chital in the Queensland dry tropics

2020 ◽  
Vol 42 (3) ◽  
pp. 221 ◽  
Author(s):  
Kurt Watter ◽  
Greg S. Baxter ◽  
Anthony Pople ◽  
Peter J. Murray
Keyword(s):  
Dry Matter ◽  
Large Scale ◽  
Potential Effect ◽  
Dry Season ◽  
Dietary Overlap ◽  
Cattle Production ◽  
Wet Season ◽  
Free Living ◽  
Dry Tropics ◽  
Axis Axis

Chital deer (Axis axis) are an ungulate species introduced to northern Queensland, Australia, in an environment where land is managed for large scale cattle production. Rainfall and pasture growth are markedly seasonal and cattle experience a nutritional shortfall each year before monsoon rain. The presence of chital is perceived by land managers to reduce dry-season grass availability and this study sought to estimate the potential effect of free-living chital on regional cattle production. Diet overlap was greatest during the wet season when both ungulates principally consumed grass, and least during the dry season when chital diet comprised only ~50% grass. Using local estimates for energy values of wet and dry season grass, and the maintenance energy requirements of chital and cattle, we estimated the relative dry-matter seasonal grass intakes of both ungulates. The grass consumed annually by 100 chital could support an additional 25 cattle during the wet season and an additional 14 cattle during the dry season.

scholarly journals Relations between Interannual Variability of Regional-Scale Indonesian Precipitation and Large-Scale Climate Modes during 1960–2007

2020 ◽  
Vol 33 (12) ◽  
pp. 5271-5291 ◽  
Author(s):  
Givo Alsepan ◽  
Shoshiro Minobe
Keyword(s):  
El Niño ◽  
Large Scale ◽  
El Nino ◽  
Regional Scale ◽  
Moisture Flux ◽  
Dry Season ◽  
Wet Season ◽  
Climate Modes ◽  
Eastern Indonesia ◽  
El Niño Modoki

AbstractRegional-scale precipitation responses over Indonesia to major climate modes in the tropical Indo–Pacific Oceans, namely canonical El Niño, El Niño Modoki, and the Indian Ocean dipole (IOD), and how the responses are related to large-scale moisture convergences are investigated. The precipitation responses, analyzed using a high-spatial-resolution (0.5° × 0.5°) terrestrial precipitation dataset for the period 1960–2007, exhibit differences between the dry (July–September) and wet (November–April) seasons. Canonical El Niño strongly reduces precipitation in central to eastern Indonesia from the dry season to the early wet season and northern Indonesia in the wet season. El Niño Modoki also reduces precipitation in central to eastern Indonesia during the dry season, but conversely increases precipitation in western Indonesia in the wet season. Moisture flux analysis indicates that corresponding to the dry (wet) season precipitation reduction due to the canonical El Niño and El Niño Modoki anomalous divergence occurs around the southern (northern) edge of the convergence zone when one of the two edges is located near the equator (10°S–15°N) associated with their seasonal migration. This largely explains the seasonality and regionality of precipitation responses to canonical El Niño and El Niño Modoki. IOD reduces precipitation in southwestern Indonesia in the dry season, associated with anomalous moisture flux divergence. The seasonality of precipitation response to IOD is likely to be controlled by the seasonality of local sea surface temperature anomalies in the eastern pole of the IOD.

scholarly journals Physical properties and concentration of aerosol particles over the Amazon tropical forest during background and biomass burning conditions

2003 ◽  
Vol 3 (4) ◽  
pp. 951-967 ◽  
Author(s):  
P. Guyon ◽  
B. Graham ◽  
J. Beck ◽  
O. Boucher ◽  
E. Gerasopoulos ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Large Scale ◽  
Marine Boundary Layer ◽  
Global Climate ◽  
Single Scattering ◽  
Dry Season ◽  
Aerosol Layer ◽  
Wet Season ◽  
Cloud Properties ◽  
Tenfold Increase

Abstract. We investigated the size distribution, scattering and absorption properties of Amazonian aerosols and the optical thickness of the aerosol layer under the pristine background conditions typical of the wet season, as well as during the biomass-burning-influenced dry season. The measurements were made during two campaigns in 1999 as part of the European contribution to the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA-EUSTACH). In moving from the wet to the dry season, median particle numbers were observed to increase from values comparable to those of the remote marine boundary layer (~400 cm-3) to values more commonly associated with urban smog (~4000 cm-3), due to a massive injection of submicron smoke particles. Aerosol optical depths at 500 nm increased from 0.05 to 0.8 on average, reaching a value of 2 during the dry season. Scattering and absorption coefficients, measured at 550 nm, showed a concomitant increase from average values of 6.8 and 0.4 Mm-1 to values of 91 and 10 Mm-1, respectively, corresponding to an estimated decrease in single-scattering albedo from ca. 0.97 to 0.91. The roughly tenfold increase in many of the measured parameters attests to the dramatic effect that extensive seasonal biomass burning (deforestation, pasture cleaning) is having on the composition and properties of aerosols over Amazonia. The potential exists for these changes to impact on regional and global climate through changes to the extinction of solar radiation as well as the alteration of cloud properties.

scholarly journals What Controls Evapotranspiration in the Amazon Basin?

2007 ◽  
Vol 8 (3) ◽  
pp. 380-395 ◽  
Author(s):  
Natalia Hasler ◽  
Roni Avissar
Keyword(s):  
Water Stress ◽  
Large Scale ◽  
Amazon Basin ◽  
Climate Models ◽  
Global Climate ◽  
Regional Climate ◽  
Dry Season ◽  
Global Climate Models ◽  
Net Radiation ◽  
Wet Season

Abstract Global climate models (GCMs) and regional climate models (RCMs) generally show a decrease in the dry season evapotranspiration (ET) rate over the entire Amazon basin. Based on anecdotal observations, it has been suggested that they probably overestimate tropical rain forest water stress. In this study, eddy covariance flux measurements from eight different towers of the Large-Scale Biosphere–Atmosphere Experiment in Amazonia (LBA) were used to provide a first look at the spatial variability and temporal cycle of ET throughout the basin. Results show strong seasonality in ET for stations near the equator (2°–3°S), with ET increasing during the dry season (June–September) and decreasing during the wet season (December–March), both correlated (0.75 to 0.94) and in phase with the net radiation annual cycle. In stations located farther south (9°–11°S) no clear seasonality could be identified in either net radiation or ET. For these more southerly stations, net radiation and ET are still correlated (0.76–0.92) in the wet season, but correlations decrease in the dry season (0–0.71), which is likely associated with water stress. For both pasture sites, located in southern Amazonia, ET decreases during the second half of the dry season, indicating progressively increased water stress. GCMs and RCMs indeed tend to overestimate dry season water stress in the Amazon basin and, therefore, should be revised to better simulate this region, which has a key role in the global hydrometeorology.

Sign in / Sign up

Export Citation Format

Share Document