IGERERANYWA RY'INGANO YA GAZI METANI

Hifashishijwe ikalita bathymétrique yakozwe mu mwaka wa 1988 na Lahmeyer afatanyije na Osae, twashyize hasi za isobathes 280 m (ubuso bugizwe n'ibara ry'umutuku kuli iyo karita) na metero 340 (ubuso bugizwe n'ibara ry'umuhondo kuli iyo karita).

Icyo gishushanyo gituma hashobora kugereranywa ubuso bw'Ikivu bubonekaho umwuka wa gazi hakulikije ubujjyakuzimu bw'ahateganyijwe kuzazamurwa iyo gazi metani. Cyerekana kandi vuba ahantu haberanye hashobora gushyirwa imashini zizajya zizamura iyo gazi, kuva ku nyigo y'uburebure bw'aho iyo gazi ili kugera ku nkengero.

Twerekanye kandi ubwinshi bw'amazi, CO2 na CH4 zili ku mubyimba wa metero icumi.

Haragaragara kuli iki gishushanyo, ku buryo bugaragara neza, itandukanyilizo riri hagati y'amazi y'ikiyaga ali heruru y'ubujyakuzimu bwa metero magana abili na mirongo itandatu (adafite umwuka wivanze mu mazi mwinshi) n'ayandi ali munsi ya metero magana abili na mirongo itandatu afite ingano nini cyane y'umwuka wivanze n'amazi. Umuntu yashobora kumva ko imibyimba ili hasi y'izo isobathes ifite gazi nyinshi cyane ishobora kuzamurwa no gutunganwa.

Kwerekana ingano ya dioxyde de carbone na metani hakulikijwe ubujyakuzimu bw'ikiyaga.

Turabona mbere na mbere ingano z'ibigereranyo zashoboye kuboneka duhereye kuli iri shusho :

ingano (mu bugali) bw'ikiyaga : 560 km3

Ingano yose y'umwuka wivanze n'amazi (TPN) : 256 Km3

Ingano yose (TPN) ya CH4 yivanze mu mazi : 65 km3

Gukwirakwiza, ku buryo buhagaritse ingano ya gazi hakulikijwe ibice bya metero 10, twerekanye ibice by'amazi bishobora kuzamurwamo gazi nyinshi ku buryo butaruhije. Iki gishushanyo kiradufasha kwerekana ikigereranyo cy'ingano za gazi ishobora kuzamurwa bidahenze cyane hakulikije ubwirunde bw'iyo gazi n'uburebure kugera ku nkombe.

Harakorwa kandi itandukanyilizo hagati y'ingano ya gazi metani yivanze mu mazi, n'ingano ya gazi metani ishobora kuzamurwa no gutunganywa (gazi y'ukuli yaboneka). Muby'ukuli, turagereranya, duhereye ku buryo bwacu bwo kubara, ko ikigereranyo cya gazi cya makumyabili ku ijana (20%) kizatakara mu mazi hasi mu ndiba y'ikivu mu gihe cyo kuvangura no kuzamura iyo gazi. Iyi mibare yose itangwa ni ingano ya metani itunganyijwe neza TPN (ingufu za bar imwe ku bushyuhe bwa 0°C).

Ku gishushanyo, ikiyaga gishobora kugabanywamo ibice bine, ku buryo ibice bitatu bifite metani ishobora kuzamurwa ku buryo bworoshye. Ibyo bice bitatu bishobora kwerekanwa hakulikije imbogamizi zishobora kuboneka mu gushyiramo ibitembo byo kuzamura iyo gazi bitewe n'ubujyakuzimu (uburebure kugera ku nkombe).

Kuzamura gazi ku bujyakuzimu bwa metero 300 (hagati ya metero 260 na metero 300 : igice cya 1).

Ingano ya metani yivanze mu mazi : 13,3 km3,
ingano ya metani ishobora kuvomwa : 10,6 km3.

Kuvoma gazi ku bujyakuzimu bwa metero 350 (hagati ya 300 - 350 : igice cya 2)

Ingano ya gazi metani yivanze mu mazi : 15 km3,
ingano ya gazi metani ishobora kuzamurwa no gutunganywa : 12 km3.

Kuzamura gazi metani ku gice kirekire cy'ikiyaga (350 - 485 m : igice cya 3)

Ingano ya gazi metani yivanze mu mazi : 14,9 km3,
ingano ya gazi ishobora kuvomwa : 11,9 km3

Kumwanzuro, kuli kilometero kibe 65 (65 km3) za gazi yivanze mu mazi mu Kivu:

28,3 km3 zishobora kuzamurwa ku buryo bworoshye kandi zatanga ingano ya gazi metani itunganye TPN
15 km3 zishobora kugerwaho ku buryo bugoranye kandi zatanga 12 km3 za gazi itunganye neza TPN
17 km3 zo zafatwa nk'aho ntacyo zatanga.

Ingano yose ya gazi ishobora kuvomwa ni: 34,5 km3

Ni ngombwa gutunganya neza uburyo bwo kuzamura gazi k'uburyo itakara mu ndiba y'ikiyaga yaba nkeya cyane mu gihe cyo kuyivangura n'amazi no kuyiyungurura. Itakara ishobora kugarukira hagati ya 20 % na 25 %. Hagomba kandi kwerekanwa ko iyo mibare itita ku ngano ya gazi yikora buli gihe. Birakomeye kugereranya uko kwisubiza (kwikora) kwa gazi, ariko imibare itangwa ubu ili hagati ya 125 Mm3 et 250 Mm3 ku mwaka.