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In acest topic vom incerca sa observam schimbari in nivelul precipitatiilor si al "apei proaspete" (fresh water) pe cele mai importante fluvii ale lumii.

Se pare ca Lacul Victoria (Izvorul Nilului) este cel mai sensibil la schimbarile climatice.
Exista o uimitoare corelatie intre activitatea Soarelui si volumul precipitatiilor in Africa Centrala.
Desigur, lacul este exploatat hidroenergetic, totusi il voi monitoriza, merita efortul!
Mai simplu spus...climat rece- nivel scazut, si invers.



http://www.eoearth.org/article/Lake_Victoria

http://www.eoearth.org/article/Major_rivers_of_the_world_(collection)?topic=48248

Ca o mica paranteza, Delta Dunarii...http://www.eoearth.org/article/Danube_Delta_Biosphere_Reserve,_Romania?topic=49514
Cate ceva si despre Marea Neagra.http://www.eoearth.org/article/Black_Sea?topic=49578

Interesant e ca te pasioneaza si regimul hidrologic al marilor fluvii ale lumii.Imi place ca acoperi o gama atat de diversa.Vezi ca din Lacul Victoria izvoraste doar Nilul Alb.Intereseaza-te si ce se mai intampla in Lacul Tana in cazul Nilului Albastru

Nu poti face altfel un studiu climatic. Altfel nu poti avea o vedere de ansamblu si inca nici pe departe nu voi putea acoperi totul. Dar acest lac e deosebit de important (Victoria)
Da, dar tot Nilul este. Oricum, conteaza mai putin ce fluviu izvoraste. Numai acest lac daca l-as studia si ar fi de ajuns se pare. Habar nu aveam de asta la inceput si anume ca e un real indicator climatic.
Sigur voi reveni cu tot ce voi afla. O sa ma interesez si despre Lacul Tana, multumesc pentru observatie.

http://pubs.giss.nasa.gov/docs/1997/1997_Dai_etal_2.pdf

Dai, A., I.Y. Fung, and A.D. Del Genio, 1997: Surface observed global land precipitation variations during 1900-1988. J. Climate, 10, 2943-2962, doi:10.1175/1520-0442(1997)010<2943:SOGLPV>2.0.CO;2.

The authors have analyzed global station data and created a gridded dataset of monthly precipitation for the 1900-1988 period. Statistical analyses suggest that discontinuities associated with instrumental errors are large for many high-latitude station records although they are unlikely to be significant for the majority of the stations. The first leading EOF in global precipitation fields is an ENSO-related pattern concentrating mostly in the low latitudes. The second leading EOF depicts a linear increasing trend (~2.4 mm/decade) in global precipitation fields during the 1900-1988 period. Consistent with the zonal precipitation trends identified in previous analyses, the EOF trend is seen as a long-term increase mostly in North America, mid- to high-latitude Eurasia, Argentina and Australia. The spatial patterns of the trend EOF and the rate of increase are generally consistent with those of the precipitation changes in increasing CO2 GCM experiments.

The North Atlantic Oscillation accounts for ~10% of December-February precipitation variance over North Atlantic surrounding regions. The mode suggests that during high-NAO-index winters, precipitation is above normal in northern (>50°N) Europe, the eastern United States, northern Africa and the Mediterranean; while below-normal precipitation occurs in southern Europe, eastern Canada and western Greenland.

Wet and dry months of one standard deviation occur at probabilities close to those of a normal distribution in midlatitudes. In the subtropics, the mean interval between two extreme events is longer. The monthly wet and dry events seldom (probability <5%) last longer than 2 months. ENSO is the single largest cause for global extreme precipitation events. Consistent with the upward trend in global precipitation, globally, the averaged mean interval between two dry months increased by ~28% from 1900-1944 to 1945-1988. The percentage of wet areas over the U.S. has more than doubled (from ~12% to >24%) since the 1970s while the percentage of dry areas has decreased by a similar amount since the 1940s. Severe droughts and floods comparable to the midwest U.S. 1988 drought and 1993 flood have occurred 2-9 times in each of several other regions of the world during this century.
http://pubs.giss.nasa.gov/abs/da03000u.html

Iata si Lacul Tana:

Totusi pe aceasta harta nici nu apare, vedem mai bine aici Lacul Victoria.
Adevaratul izvor al Nilului, dupa parerea mea.
Aveam si un apus de soare superb de pe Lacul Tana...nu s-a salvat.

http://en.wikipedia.org/wiki/Lake_Tana Am vazut si documentar cu asa ceva, a aratat si unde se formeaza Nilul propriu-zis din White si Blue Nile

The Blue Nile (Ge'ez ጥቁር ዓባይ Ṭiqūr ʿĀbbāy (Black Abay) to Ethiopians; Arabic: النيل الأزرق‎; transliterated: an-Nīl al-Azraq) springs from Lake Tana in the Ethiopian Highlands. The Blue Nile flows about 1,400 kilometres to Khartoum, where the Blue Nile and White Nile join to form the Nile. Ninety percent of the water and ninety-six percent of the transported sediment carried by the Nile[17] originates in Ethiopia, with fifty-nine percent of the water from the Blue Nile (the rest being from the Tekezé, Atbarah, Sobat, and small tributaries). The erosion and transportation of silt only occurs during the Ethiopian rainy season in the summer, however, when rainfall is especially high on the Ethiopian Plateau; the rest of the year, the great rivers draining Ethiopia into the Nile (Sobat, Blue Nile, Tekezé, and Atbarah) have a weaker flow.
The flow of the Blue Nile varies considerably over its yearly cycle and is the main contribution to the large natural variation of the Nile flow. During the dry season the natural discharge of the Blue Nile can be as low as 113 m3/s (4,000 cu ft/s), although upstream dams regulate the flow of the river. During the wet season the peak flow of the Blue Nile often exceeds 5,663 m3/s (200,000 cu ft/s) in late August (a difference of a factor of 50).
Before the placement of dams on the river the yearly discharge varied by a factor of 15 at Aswan. Peak flows of over 8,212 m3/s (290,000 cu ft/s) occurred during late August and early September, and minimum flows of about 552 m3/s (19,500 cu ft/s) occurred during late April and early May.

Nu mai deschid sa citesc, am program drastic somn de la ora 22.
Nu are cine sa-mi strige, asa ca strig singura sa inchid!
Dar maine intru si citesc, noapte buna!

Nu stiu dupa ce criterii, eu pun cel mai lung traseu. Nu dupa debit.
Dar poate e mai putin important. Ideia centrala e ca Lacul Victoria e un indicator climatic.
Hmmm...pai Lacul Victoria deja e un regulator de debit...in sfarsit...cred ca daca mai caut, am dreptate si la debit, dar am altele in plan azi.

Dar are legatura cu precipitatiile si volumul Nilului.De fapt, marile inundatii si totodata sedimentele transportate care fac posibila agricultura in tari precum Egipt se datoreaza Nilului Albastru.Musonul din Etiopia are asadar un rol foarte important in debitul multianual al Nilului.Nu trebuie privit doar Lacul Victoria, ci per ansablu toti tributarii, inclusiv cei mai mici, dar cu rol esential.La o adica, musonul din Etiopia si comportamentul acestuia reprezinta un indicator climatic cel putin la fel de important.Crezi ca el nu "simte" variatiile climatice ? Daca tot tratezi o problema, trateaz-o in intregime, nu partial

De acord, dar daca nu era Victoria, si de acolo veneau aluviuni.
Oricum, multumesc mult pentru observatii!!

Ma gandesc ca ai putea sa studiezi si fluvii precum Gangele, ca sa vezi cum se comporta acesta in functie de intensitatea si durata musonului din India la nivel anual, decenial sau chiar multidecenial.Poate si acolo ai observa indicii in ceea ce priveste "comportamentul" climatic

Cu siguranta voi ajunge si acolo.Pana acum doar mi-am extins teritoriul ca sa zic asa, urmeaza studiul intensiv. Am fost precum gaina in mijlocul gramezii, am imprastiat-o. Voi lua fiecare portiune in parte.
Sigur, imi va lua timp, dar e bine ca imi omor timpul. Va trebui sa aleg statiile Sahariene si sa iau statisticile lor. Vor fi utile doar acelea la care gasesc actualizari lunare.
Totusi tin capul sus, sa nu cad in enorma greseala de a fi cufundata in ceva, ca sa nu vad si alte lucruri.
Precum un radar trebuie sa fiu, precum acel flash.
Totusi nici iarna nu e un sezon mort. De fapt motorul schimbarilor climatice e Atlanticul de Nord.
Face legatura intre desert si pol...
Celulele Walker...de fapt toate denumirile AO,NAO,PDO,SOI si cum le mai spune, sunt celule Walker.
Cu cat sunt mai spre Pol, cu atat mai complexe...AMO...PDO...multi...decadal...
Totusi un vulcan mai marisor cand erupe sau cand Soarele e intr-un minim, se vede clar influenta.
Atmosfera stocheaza putina energie totusi. Oceanele ce mai compenseaza...prin fluviile lor-curentii.